tsvector_op.c

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/*-------------------------------------------------------------------------
 *
 * tsvector_op.c
 *    operations over tsvector
 *
 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/tsvector_op.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include <limits.h>

#include "access/htup_details.h"
#include "catalog/namespace.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "executor/spi.h"
#include "funcapi.h"
#include "lib/qunique.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "parser/parse_coerce.h"
#include "tsearch/ts_utils.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/regproc.h"
#include "utils/rel.h"


typedef struct
{
    WordEntry  *arrb;
    WordEntry  *arre;
    char       *values;
    char       *operand;
} CHKVAL;


typedef struct StatEntry
{
    uint32      ndoc;           /* zero indicates that we were already here
                                 * while walking through the tree */
    uint32      nentry;
    struct StatEntry *left;
    struct StatEntry *right;
    uint32      lenlexeme;
    char        lexeme[FLEXIBLE_ARRAY_MEMBER];
} StatEntry;

#define STATENTRYHDRSZ  (offsetof(StatEntry, lexeme))

typedef struct
{
    int32       weight;

    uint32      maxdepth;

    StatEntry **stack;
    uint32      stackpos;

    StatEntry  *root;
} TSVectorStat;

/* TS_execute requires ternary logic to handle NOT with phrase matches */
typedef enum
{
    TS_NO,                      /* definitely no match */
    TS_YES,                     /* definitely does match */
    TS_MAYBE                    /* can't verify match for lack of pos data */
} TSTernaryValue;


static TSTernaryValue TS_execute_recurse(QueryItem *curitem, void *arg,
                                         uint32 flags,
                                         TSExecuteCallback chkcond);
static int  tsvector_bsearch(const TSVector tsv, char *lexeme, int lexeme_len);
static Datum tsvector_update_trigger(PG_FUNCTION_ARGS, bool config_column);


/*
 * Order: haspos, len, word, for all positions (pos, weight)
 */
static int
silly_cmp_tsvector(const TSVector a, const TSVector b)
{
    if (VARSIZE(a) < VARSIZE(b))
        return -1;
    else if (VARSIZE(a) > VARSIZE(b))
        return 1;
    else if (a->size < b->size)
        return -1;
    else if (a->size > b->size)
        return 1;
    else
    {
        WordEntry  *aptr = ARRPTR(a);
        WordEntry  *bptr = ARRPTR(b);
        int         i = 0;
        int         res;


        for (i = 0; i < a->size; i++)
        {
            if (aptr->haspos != bptr->haspos)
            {
                return (aptr->haspos > bptr->haspos) ? -1 : 1;
            }
            else if ((res = tsCompareString(STRPTR(a) + aptr->pos, aptr->len, STRPTR(b) + bptr->pos, bptr->len, false)) != 0)
            {
                return res;
            }
            else if (aptr->haspos)
            {
                WordEntryPos *ap = POSDATAPTR(a, aptr);
                WordEntryPos *bp = POSDATAPTR(b, bptr);
                int         j;

                if (POSDATALEN(a, aptr) != POSDATALEN(b, bptr))
                    return (POSDATALEN(a, aptr) > POSDATALEN(b, bptr)) ? -1 : 1;

                for (j = 0; j < POSDATALEN(a, aptr); j++)
                {
                    if (WEP_GETPOS(*ap) != WEP_GETPOS(*bp))
                    {
                        return (WEP_GETPOS(*ap) > WEP_GETPOS(*bp)) ? -1 : 1;
                    }
                    else if (WEP_GETWEIGHT(*ap) != WEP_GETWEIGHT(*bp))
                    {
                        return (WEP_GETWEIGHT(*ap) > WEP_GETWEIGHT(*bp)) ? -1 : 1;
                    }
                    ap++, bp++;
                }
            }

            aptr++;
            bptr++;
        }
    }

    return 0;
}

#define TSVECTORCMPFUNC( type, action, ret )            \
Datum                                                   \
tsvector_##type(PG_FUNCTION_ARGS)                       \
{                                                       \
    TSVector    a = PG_GETARG_TSVECTOR(0);              \
    TSVector    b = PG_GETARG_TSVECTOR(1);              \
    int         res = silly_cmp_tsvector(a, b);         \
    PG_FREE_IF_COPY(a,0);                               \
    PG_FREE_IF_COPY(b,1);                               \
    PG_RETURN_##ret( res action 0 );                    \
}   \
/* keep compiler quiet - no extra ; */                  \
extern int no_such_variable

TSVECTORCMPFUNC(lt, <, BOOL);
TSVECTORCMPFUNC(le, <=, BOOL);
TSVECTORCMPFUNC(eq, ==, BOOL);
TSVECTORCMPFUNC(ge, >=, BOOL);
TSVECTORCMPFUNC(gt, >, BOOL);
TSVECTORCMPFUNC(ne, !=, BOOL);
TSVECTORCMPFUNC(cmp, +, INT32);

Datum
tsvector_strip(PG_FUNCTION_ARGS)
{
    TSVector    in = PG_GETARG_TSVECTOR(0);
    TSVector    out;
    int         i,
                len = 0;
    WordEntry  *arrin = ARRPTR(in),
               *arrout;
    char       *cur;

    for (i = 0; i < in->size; i++)
        len += arrin[i].len;

    len = CALCDATASIZE(in->size, len);
    out = (TSVector) palloc0(len);
    SET_VARSIZE(out, len);
    out->size = in->size;
    arrout = ARRPTR(out);
    cur = STRPTR(out);
    for (i = 0; i < in->size; i++)
    {
        memcpy(cur, STRPTR(in) + arrin[i].pos, arrin[i].len);
        arrout[i].haspos = 0;
        arrout[i].len = arrin[i].len;
        arrout[i].pos = cur - STRPTR(out);
        cur += arrout[i].len;
    }

    PG_FREE_IF_COPY(in, 0);
    PG_RETURN_POINTER(out);
}

Datum
tsvector_length(PG_FUNCTION_ARGS)
{
    TSVector    in = PG_GETARG_TSVECTOR(0);
    int32       ret = in->size;

    PG_FREE_IF_COPY(in, 0);
    PG_RETURN_INT32(ret);
}

Datum
tsvector_setweight(PG_FUNCTION_ARGS)
{
    TSVector    in = PG_GETARG_TSVECTOR(0);
    char        cw = PG_GETARG_CHAR(1);
    TSVector    out;
    int         i,
                j;
    WordEntry  *entry;
    WordEntryPos *p;
    int         w = 0;

    switch (cw)
    {
        case 'A':
        case 'a':
            w = 3;
            break;
        case 'B':
        case 'b':
            w = 2;
            break;
        case 'C':
        case 'c':
            w = 1;
            break;
        case 'D':
        case 'd':
            w = 0;
            break;
        default:
            /* internal error */
            elog(ERROR, "unrecognized weight: %d", cw);
    }

    out = (TSVector) palloc(VARSIZE(in));
    memcpy(out, in, VARSIZE(in));
    entry = ARRPTR(out);
    i = out->size;
    while (i--)
    {
        if ((j = POSDATALEN(out, entry)) != 0)
        {
            p = POSDATAPTR(out, entry);
            while (j--)
            {
                WEP_SETWEIGHT(*p, w);
                p++;
            }
        }
        entry++;
    }

    PG_FREE_IF_COPY(in, 0);
    PG_RETURN_POINTER(out);
}

/*
 * setweight(tsin tsvector, char_weight "char", lexemes "text"[])
 *
 * Assign weight w to elements of tsin that are listed in lexemes.
 */
Datum
tsvector_setweight_by_filter(PG_FUNCTION_ARGS)
{
    TSVector    tsin = PG_GETARG_TSVECTOR(0);
    char        char_weight = PG_GETARG_CHAR(1);
    ArrayType  *lexemes = PG_GETARG_ARRAYTYPE_P(2);

    TSVector    tsout;
    int         i,
                j,
                nlexemes,
                weight;
    WordEntry  *entry;
    Datum      *dlexemes;
    bool       *nulls;

    switch (char_weight)
    {
        case 'A':
        case 'a':
            weight = 3;
            break;
        case 'B':
        case 'b':
            weight = 2;
            break;
        case 'C':
        case 'c':
            weight = 1;
            break;
        case 'D':
        case 'd':
            weight = 0;
            break;
        default:
            /* internal error */
            elog(ERROR, "unrecognized weight: %c", char_weight);
    }

    tsout = (TSVector) palloc(VARSIZE(tsin));
    memcpy(tsout, tsin, VARSIZE(tsin));
    entry = ARRPTR(tsout);

    deconstruct_array(lexemes, TEXTOID, -1, false, TYPALIGN_INT,
                      &dlexemes, &nulls, &nlexemes);

    /*
     * Assuming that lexemes array is significantly shorter than tsvector we
     * can iterate through lexemes performing binary search of each lexeme
     * from lexemes in tsvector.
     */
    for (i = 0; i < nlexemes; i++)
    {
        char       *lex;
        int         lex_len,
                    lex_pos;

        if (nulls[i])
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("lexeme array may not contain nulls")));

        lex = VARDATA(dlexemes[i]);
        lex_len = VARSIZE(dlexemes[i]) - VARHDRSZ;
        lex_pos = tsvector_bsearch(tsout, lex, lex_len);

        if (lex_pos >= 0 && (j = POSDATALEN(tsout, entry + lex_pos)) != 0)
        {
            WordEntryPos *p = POSDATAPTR(tsout, entry + lex_pos);

            while (j--)
            {
                WEP_SETWEIGHT(*p, weight);
                p++;
            }
        }
    }

    PG_FREE_IF_COPY(tsin, 0);
    PG_FREE_IF_COPY(lexemes, 2);

    PG_RETURN_POINTER(tsout);
}

#define compareEntry(pa, a, pb, b) \
    tsCompareString((pa) + (a)->pos, (a)->len,  \
                    (pb) + (b)->pos, (b)->len,  \
                    false)

/*
 * Add positions from src to dest after offsetting them by maxpos.
 * Return the number added (might be less than expected due to overflow)
 */
static int32
add_pos(TSVector src, WordEntry *srcptr,
        TSVector dest, WordEntry *destptr,
        int32 maxpos)
{
    uint16     *clen = &_POSVECPTR(dest, destptr)->npos;
    int         i;
    uint16      slen = POSDATALEN(src, srcptr),
                startlen;
    WordEntryPos *spos = POSDATAPTR(src, srcptr),
               *dpos = POSDATAPTR(dest, destptr);

    if (!destptr->haspos)
        *clen = 0;

    startlen = *clen;
    for (i = 0;
         i < slen && *clen < MAXNUMPOS &&
         (*clen == 0 || WEP_GETPOS(dpos[*clen - 1]) != MAXENTRYPOS - 1);
         i++)
    {
        WEP_SETWEIGHT(dpos[*clen], WEP_GETWEIGHT(spos[i]));
        WEP_SETPOS(dpos[*clen], LIMITPOS(WEP_GETPOS(spos[i]) + maxpos));
        (*clen)++;
    }

    if (*clen != startlen)
        destptr->haspos = 1;
    return *clen - startlen;
}

/*
 * Perform binary search of given lexeme in TSVector.
 * Returns lexeme position in TSVector's entry array or -1 if lexeme wasn't
 * found.
 */
static int
tsvector_bsearch(const TSVector tsv, char *lexeme, int lexeme_len)
{
    WordEntry  *arrin = ARRPTR(tsv);
    int         StopLow = 0,
                StopHigh = tsv->size,
                StopMiddle,
                cmp;

    while (StopLow < StopHigh)
    {
        StopMiddle = (StopLow + StopHigh) / 2;

        cmp = tsCompareString(lexeme, lexeme_len,
                              STRPTR(tsv) + arrin[StopMiddle].pos,
                              arrin[StopMiddle].len,
                              false);

        if (cmp < 0)
            StopHigh = StopMiddle;
        else if (cmp > 0)
            StopLow = StopMiddle + 1;
        else                    /* found it */
            return StopMiddle;
    }

    return -1;
}

/*
 * qsort comparator functions
 */

static int
compare_int(const void *va, const void *vb)
{
    int         a = *((const int *) va);
    int         b = *((const int *) vb);

    if (a == b)
        return 0;
    return (a > b) ? 1 : -1;
}

static int
compare_text_lexemes(const void *va, const void *vb)
{
    Datum       a = *((const Datum *) va);
    Datum       b = *((const Datum *) vb);
    char       *alex = VARDATA_ANY(a);
    int         alex_len = VARSIZE_ANY_EXHDR(a);
    char       *blex = VARDATA_ANY(b);
    int         blex_len = VARSIZE_ANY_EXHDR(b);

    return tsCompareString(alex, alex_len, blex, blex_len, false);
}

/*
 * Internal routine to delete lexemes from TSVector by array of offsets.
 *
 * int *indices_to_delete -- array of lexeme offsets to delete (modified here!)
 * int indices_count -- size of that array
 *
 * Returns new TSVector without given lexemes along with their positions
 * and weights.
 */
static TSVector
tsvector_delete_by_indices(TSVector tsv, int *indices_to_delete,
                           int indices_count)
{
    TSVector    tsout;
    WordEntry  *arrin = ARRPTR(tsv),
               *arrout;
    char       *data = STRPTR(tsv),
               *dataout;
    int         i,              /* index in arrin */
                j,              /* index in arrout */
                k,              /* index in indices_to_delete */
                curoff;         /* index in dataout area */

    /*
     * Sort the filter array to simplify membership checks below.  Also, get
     * rid of any duplicate entries, so that we can assume that indices_count
     * is exactly equal to the number of lexemes that will be removed.
     */
    if (indices_count > 1)
    {
        qsort(indices_to_delete, indices_count, sizeof(int), compare_int);
        indices_count = qunique(indices_to_delete, indices_count, sizeof(int),
                                compare_int);
    }

    /*
     * Here we overestimate tsout size, since we don't know how much space is
     * used by the deleted lexeme(s).  We will set exact size below.
     */
    tsout = (TSVector) palloc0(VARSIZE(tsv));

    /* This count must be correct because STRPTR(tsout) relies on it. */
    tsout->size = tsv->size - indices_count;

    /*
     * Copy tsv to tsout, skipping lexemes listed in indices_to_delete.
     */
    arrout = ARRPTR(tsout);
    dataout = STRPTR(tsout);
    curoff = 0;
    for (i = j = k = 0; i < tsv->size; i++)
    {
        /*
         * If current i is present in indices_to_delete, skip this lexeme.
         * Since indices_to_delete is already sorted, we only need to check
         * the current (k'th) entry.
         */
        if (k < indices_count && i == indices_to_delete[k])
        {
            k++;
            continue;
        }

        /* Copy lexeme and its positions and weights */
        memcpy(dataout + curoff, data + arrin[i].pos, arrin[i].len);
        arrout[j].haspos = arrin[i].haspos;
        arrout[j].len = arrin[i].len;
        arrout[j].pos = curoff;
        curoff += arrin[i].len;
        if (arrin[i].haspos)
        {
            int         len = POSDATALEN(tsv, arrin + i) * sizeof(WordEntryPos)
            + sizeof(uint16);

            curoff = SHORTALIGN(curoff);
            memcpy(dataout + curoff,
                   STRPTR(tsv) + SHORTALIGN(arrin[i].pos + arrin[i].len),
                   len);
            curoff += len;
        }

        j++;
    }

    /*
     * k should now be exactly equal to indices_count. If it isn't then the
     * caller provided us with indices outside of [0, tsv->size) range and
     * estimation of tsout's size is wrong.
     */
    Assert(k == indices_count);

    SET_VARSIZE(tsout, CALCDATASIZE(tsout->size, curoff));
    return tsout;
}

/*
 * Delete given lexeme from tsvector.
 * Implementation of user-level ts_delete(tsvector, text).
 */
Datum
tsvector_delete_str(PG_FUNCTION_ARGS)
{
    TSVector    tsin = PG_GETARG_TSVECTOR(0),
                tsout;
    text       *tlexeme = PG_GETARG_TEXT_PP(1);
    char       *lexeme = VARDATA_ANY(tlexeme);
    int         lexeme_len = VARSIZE_ANY_EXHDR(tlexeme),
                skip_index;

    if ((skip_index = tsvector_bsearch(tsin, lexeme, lexeme_len)) == -1)
        PG_RETURN_POINTER(tsin);

    tsout = tsvector_delete_by_indices(tsin, &skip_index, 1);

    PG_FREE_IF_COPY(tsin, 0);
    PG_FREE_IF_COPY(tlexeme, 1);
    PG_RETURN_POINTER(tsout);
}

/*
 * Delete given array of lexemes from tsvector.
 * Implementation of user-level ts_delete(tsvector, text[]).
 */
Datum
tsvector_delete_arr(PG_FUNCTION_ARGS)
{
    TSVector    tsin = PG_GETARG_TSVECTOR(0),
                tsout;
    ArrayType  *lexemes = PG_GETARG_ARRAYTYPE_P(1);
    int         i,
                nlex,
                skip_count,
               *skip_indices;
    Datum      *dlexemes;
    bool       *nulls;

    deconstruct_array(lexemes, TEXTOID, -1, false, TYPALIGN_INT,
                      &dlexemes, &nulls, &nlex);

    /*
     * In typical use case array of lexemes to delete is relatively small. So
     * here we optimize things for that scenario: iterate through lexarr
     * performing binary search of each lexeme from lexarr in tsvector.
     */
    skip_indices = palloc0(nlex * sizeof(int));
    for (i = skip_count = 0; i < nlex; i++)
    {
        char       *lex;
        int         lex_len,
                    lex_pos;

        if (nulls[i])
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("lexeme array may not contain nulls")));

        lex = VARDATA(dlexemes[i]);
        lex_len = VARSIZE(dlexemes[i]) - VARHDRSZ;
        lex_pos = tsvector_bsearch(tsin, lex, lex_len);

        if (lex_pos >= 0)
            skip_indices[skip_count++] = lex_pos;
    }

    tsout = tsvector_delete_by_indices(tsin, skip_indices, skip_count);

    pfree(skip_indices);
    PG_FREE_IF_COPY(tsin, 0);
    PG_FREE_IF_COPY(lexemes, 1);

    PG_RETURN_POINTER(tsout);
}

/*
 * Expand tsvector as table with following columns:
 *     lexeme: lexeme text
 *     positions: integer array of lexeme positions
 *     weights: char array of weights corresponding to positions
 */
Datum
tsvector_unnest(PG_FUNCTION_ARGS)
{
    FuncCallContext *funcctx;
    TSVector    tsin;

    if (SRF_IS_FIRSTCALL())
    {
        MemoryContext oldcontext;
        TupleDesc   tupdesc;

        funcctx = SRF_FIRSTCALL_INIT();
        oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

        tupdesc = CreateTemplateTupleDesc(3);
        TupleDescInitEntry(tupdesc, (AttrNumber) 1, "lexeme",
                           TEXTOID, -1, 0);
        TupleDescInitEntry(tupdesc, (AttrNumber) 2, "positions",
                           INT2ARRAYOID, -1, 0);
        TupleDescInitEntry(tupdesc, (AttrNumber) 3, "weights",
                           TEXTARRAYOID, -1, 0);
        funcctx->tuple_desc = BlessTupleDesc(tupdesc);

        funcctx->user_fctx = PG_GETARG_TSVECTOR_COPY(0);

        MemoryContextSwitchTo(oldcontext);
    }

    funcctx = SRF_PERCALL_SETUP();
    tsin = (TSVector) funcctx->user_fctx;

    if (funcctx->call_cntr < tsin->size)
    {
        WordEntry  *arrin = ARRPTR(tsin);
        char       *data = STRPTR(tsin);
        HeapTuple   tuple;
        int         j,
                    i = funcctx->call_cntr;
        bool        nulls[] = {false, false, false};
        Datum       values[3];

        values[0] = PointerGetDatum(cstring_to_text_with_len(data + arrin[i].pos, arrin[i].len));

        if (arrin[i].haspos)
        {
            WordEntryPosVector *posv;
            Datum      *positions;
            Datum      *weights;
            char        weight;

            /*
             * Internally tsvector stores position and weight in the same
             * uint16 (2 bits for weight, 14 for position). Here we extract
             * that in two separate arrays.
             */
            posv = _POSVECPTR(tsin, arrin + i);
            positions = palloc(posv->npos * sizeof(Datum));
            weights = palloc(posv->npos * sizeof(Datum));
            for (j = 0; j < posv->npos; j++)
            {
                positions[j] = Int16GetDatum(WEP_GETPOS(posv->pos[j]));
                weight = 'D' - WEP_GETWEIGHT(posv->pos[j]);
                weights[j] = PointerGetDatum(cstring_to_text_with_len(&weight,
                                                                      1));
            }

            values[1] = PointerGetDatum(construct_array(positions, posv->npos,
                                                        INT2OID, 2, true, TYPALIGN_SHORT));
            values[2] = PointerGetDatum(construct_array(weights, posv->npos,
                                                        TEXTOID, -1, false, TYPALIGN_INT));
        }
        else
        {
            nulls[1] = nulls[2] = true;
        }

        tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
        SRF_RETURN_NEXT(funcctx, HeapTupleGetDatum(tuple));
    }
    else
    {
        SRF_RETURN_DONE(funcctx);
    }
}

/*
 * Convert tsvector to array of lexemes.
 */
Datum
tsvector_to_array(PG_FUNCTION_ARGS)
{
    TSVector    tsin = PG_GETARG_TSVECTOR(0);
    WordEntry  *arrin = ARRPTR(tsin);
    Datum      *elements;
    int         i;
    ArrayType  *array;

    elements = palloc(tsin->size * sizeof(Datum));

    for (i = 0; i < tsin->size; i++)
    {
        elements[i] = PointerGetDatum(cstring_to_text_with_len(STRPTR(tsin) + arrin[i].pos,
                                                               arrin[i].len));
    }

    array = construct_array(elements, tsin->size, TEXTOID, -1, false, TYPALIGN_INT);

    pfree(elements);
    PG_FREE_IF_COPY(tsin, 0);
    PG_RETURN_POINTER(array);
}

/*
 * Build tsvector from array of lexemes.
 */
Datum
array_to_tsvector(PG_FUNCTION_ARGS)
{
    ArrayType  *v = PG_GETARG_ARRAYTYPE_P(0);
    TSVector    tsout;
    Datum      *dlexemes;
    WordEntry  *arrout;
    bool       *nulls;
    int         nitems,
                i,
                tslen,
                datalen = 0;
    char       *cur;

    deconstruct_array(v, TEXTOID, -1, false, TYPALIGN_INT, &dlexemes, &nulls, &nitems);

    /* Reject nulls (maybe we should just ignore them, instead?) */
    for (i = 0; i < nitems; i++)
    {
        if (nulls[i])
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("lexeme array may not contain nulls")));
    }

    /* Sort and de-dup, because this is required for a valid tsvector. */
    if (nitems > 1)
    {
        qsort(dlexemes, nitems, sizeof(Datum), compare_text_lexemes);
        nitems = qunique(dlexemes, nitems, sizeof(Datum),
                         compare_text_lexemes);
    }

    /* Calculate space needed for surviving lexemes. */
    for (i = 0; i < nitems; i++)
        datalen += VARSIZE(dlexemes[i]) - VARHDRSZ;
    tslen = CALCDATASIZE(nitems, datalen);

    /* Allocate and fill tsvector. */
    tsout = (TSVector) palloc0(tslen);
    SET_VARSIZE(tsout, tslen);
    tsout->size = nitems;

    arrout = ARRPTR(tsout);
    cur = STRPTR(tsout);
    for (i = 0; i < nitems; i++)
    {
        char       *lex = VARDATA(dlexemes[i]);
        int         lex_len = VARSIZE(dlexemes[i]) - VARHDRSZ;

        memcpy(cur, lex, lex_len);
        arrout[i].haspos = 0;
        arrout[i].len = lex_len;
        arrout[i].pos = cur - STRPTR(tsout);
        cur += lex_len;
    }

    PG_FREE_IF_COPY(v, 0);
    PG_RETURN_POINTER(tsout);
}

/*
 * ts_filter(): keep only lexemes with given weights in tsvector.
 */
Datum
tsvector_filter(PG_FUNCTION_ARGS)
{
    TSVector    tsin = PG_GETARG_TSVECTOR(0),
                tsout;
    ArrayType  *weights = PG_GETARG_ARRAYTYPE_P(1);
    WordEntry  *arrin = ARRPTR(tsin),
               *arrout;
    char       *datain = STRPTR(tsin),
               *dataout;
    Datum      *dweights;
    bool       *nulls;
    int         nweights;
    int         i,
                j;
    int         cur_pos = 0;
    char        mask = 0;

    deconstruct_array(weights, CHAROID, 1, true, TYPALIGN_CHAR,
                      &dweights, &nulls, &nweights);

    for (i = 0; i < nweights; i++)
    {
        char        char_weight;

        if (nulls[i])
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("weight array may not contain nulls")));

        char_weight = DatumGetChar(dweights[i]);
        switch (char_weight)
        {
            case 'A':
            case 'a':
                mask = mask | 8;
                break;
            case 'B':
            case 'b':
                mask = mask | 4;
                break;
            case 'C':
            case 'c':
                mask = mask | 2;
                break;
            case 'D':
            case 'd':
                mask = mask | 1;
                break;
            default:
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                         errmsg("unrecognized weight: \"%c\"", char_weight)));
        }
    }

    tsout = (TSVector) palloc0(VARSIZE(tsin));
    tsout->size = tsin->size;
    arrout = ARRPTR(tsout);
    dataout = STRPTR(tsout);

    for (i = j = 0; i < tsin->size; i++)
    {
        WordEntryPosVector *posvin,
                   *posvout;
        int         npos = 0;
        int         k;

        if (!arrin[i].haspos)
            continue;

        posvin = _POSVECPTR(tsin, arrin + i);
        posvout = (WordEntryPosVector *)
            (dataout + SHORTALIGN(cur_pos + arrin[i].len));

        for (k = 0; k < posvin->npos; k++)
        {
            if (mask & (1 << WEP_GETWEIGHT(posvin->pos[k])))
                posvout->pos[npos++] = posvin->pos[k];
        }

        /* if no satisfactory positions found, skip lexeme */
        if (!npos)
            continue;

        arrout[j].haspos = true;
        arrout[j].len = arrin[i].len;
        arrout[j].pos = cur_pos;

        memcpy(dataout + cur_pos, datain + arrin[i].pos, arrin[i].len);
        posvout->npos = npos;
        cur_pos += SHORTALIGN(arrin[i].len);
        cur_pos += POSDATALEN(tsout, arrout + j) * sizeof(WordEntryPos) +
            sizeof(uint16);
        j++;
    }

    tsout->size = j;
    if (dataout != STRPTR(tsout))
        memmove(STRPTR(tsout), dataout, cur_pos);

    SET_VARSIZE(tsout, CALCDATASIZE(tsout->size, cur_pos));

    PG_FREE_IF_COPY(tsin, 0);
    PG_RETURN_POINTER(tsout);
}

Datum
tsvector_concat(PG_FUNCTION_ARGS)
{
    TSVector    in1 = PG_GETARG_TSVECTOR(0);
    TSVector    in2 = PG_GETARG_TSVECTOR(1);
    TSVector    out;
    WordEntry  *ptr;
    WordEntry  *ptr1,
               *ptr2;
    WordEntryPos *p;
    int         maxpos = 0,
                i,
                j,
                i1,
                i2,
                dataoff,
                output_bytes,
                output_size;
    char       *data,
               *data1,
               *data2;

    /* Get max position in in1; we'll need this to offset in2's positions */
    ptr = ARRPTR(in1);
    i = in1->size;
    while (i--)
    {
        if ((j = POSDATALEN(in1, ptr)) != 0)
        {
            p = POSDATAPTR(in1, ptr);
            while (j--)
            {
                if (WEP_GETPOS(*p) > maxpos)
                    maxpos = WEP_GETPOS(*p);
                p++;
            }
        }
        ptr++;
    }

    ptr1 = ARRPTR(in1);
    ptr2 = ARRPTR(in2);
    data1 = STRPTR(in1);
    data2 = STRPTR(in2);
    i1 = in1->size;
    i2 = in2->size;

    /*
     * Conservative estimate of space needed.  We might need all the data in
     * both inputs, and conceivably add a pad byte before position data for
     * each item where there was none before.
     */
    output_bytes = VARSIZE(in1) + VARSIZE(in2) + i1 + i2;

    out = (TSVector) palloc0(output_bytes);
    SET_VARSIZE(out, output_bytes);

    /*
     * We must make out->size valid so that STRPTR(out) is sensible.  We'll
     * collapse out any unused space at the end.
     */
    out->size = in1->size + in2->size;

    ptr = ARRPTR(out);
    data = STRPTR(out);
    dataoff = 0;
    while (i1 && i2)
    {
        int         cmp = compareEntry(data1, ptr1, data2, ptr2);

        if (cmp < 0)
        {                       /* in1 first */
            ptr->haspos = ptr1->haspos;
            ptr->len = ptr1->len;
            memcpy(data + dataoff, data1 + ptr1->pos, ptr1->len);
            ptr->pos = dataoff;
            dataoff += ptr1->len;
            if (ptr->haspos)
            {
                dataoff = SHORTALIGN(dataoff);
                memcpy(data + dataoff, _POSVECPTR(in1, ptr1), POSDATALEN(in1, ptr1) * sizeof(WordEntryPos) + sizeof(uint16));
                dataoff += POSDATALEN(in1, ptr1) * sizeof(WordEntryPos) + sizeof(uint16);
            }

            ptr++;
            ptr1++;
            i1--;
        }
        else if (cmp > 0)
        {                       /* in2 first */
            ptr->haspos = ptr2->haspos;
            ptr->len = ptr2->len;
            memcpy(data + dataoff, data2 + ptr2->pos, ptr2->len);
            ptr->pos = dataoff;
            dataoff += ptr2->len;
            if (ptr->haspos)
            {
                int         addlen = add_pos(in2, ptr2, out, ptr, maxpos);

                if (addlen == 0)
                    ptr->haspos = 0;
                else
                {
                    dataoff = SHORTALIGN(dataoff);
                    dataoff += addlen * sizeof(WordEntryPos) + sizeof(uint16);
                }
            }

            ptr++;
            ptr2++;
            i2--;
        }
        else
        {
            ptr->haspos = ptr1->haspos | ptr2->haspos;
            ptr->len = ptr1->len;
            memcpy(data + dataoff, data1 + ptr1->pos, ptr1->len);
            ptr->pos = dataoff;
            dataoff += ptr1->len;
            if (ptr->haspos)
            {
                if (ptr1->haspos)
                {
                    dataoff = SHORTALIGN(dataoff);
                    memcpy(data + dataoff, _POSVECPTR(in1, ptr1), POSDATALEN(in1, ptr1) * sizeof(WordEntryPos) + sizeof(uint16));
                    dataoff += POSDATALEN(in1, ptr1) * sizeof(WordEntryPos) + sizeof(uint16);
                    if (ptr2->haspos)
                        dataoff += add_pos(in2, ptr2, out, ptr, maxpos) * sizeof(WordEntryPos);
                }
                else            /* must have ptr2->haspos */
                {
                    int         addlen = add_pos(in2, ptr2, out, ptr, maxpos);

                    if (addlen == 0)
                        ptr->haspos = 0;
                    else
                    {
                        dataoff = SHORTALIGN(dataoff);
                        dataoff += addlen * sizeof(WordEntryPos) + sizeof(uint16);
                    }
                }
            }

            ptr++;
            ptr1++;
            ptr2++;
            i1--;
            i2--;
        }
    }

    while (i1)
    {
        ptr->haspos = ptr1->haspos;
        ptr->len = ptr1->len;
        memcpy(data + dataoff, data1 + ptr1->pos, ptr1->len);
        ptr->pos = dataoff;
        dataoff += ptr1->len;
        if (ptr->haspos)
        {
            dataoff = SHORTALIGN(dataoff);
            memcpy(data + dataoff, _POSVECPTR(in1, ptr1), POSDATALEN(in1, ptr1) * sizeof(WordEntryPos) + sizeof(uint16));
            dataoff += POSDATALEN(in1, ptr1) * sizeof(WordEntryPos) + sizeof(uint16);
        }

        ptr++;
        ptr1++;
        i1--;
    }

    while (i2)
    {
        ptr->haspos = ptr2->haspos;
        ptr->len = ptr2->len;
        memcpy(data + dataoff, data2 + ptr2->pos, ptr2->len);
        ptr->pos = dataoff;
        dataoff += ptr2->len;
        if (ptr->haspos)
        {
            int         addlen = add_pos(in2, ptr2, out, ptr, maxpos);

            if (addlen == 0)
                ptr->haspos = 0;
            else
            {
                dataoff = SHORTALIGN(dataoff);
                dataoff += addlen * sizeof(WordEntryPos) + sizeof(uint16);
            }
        }

        ptr++;
        ptr2++;
        i2--;
    }

    /*
     * Instead of checking each offset individually, we check for overflow of
     * pos fields once at the end.
     */
    if (dataoff > MAXSTRPOS)
        ereport(ERROR,
                (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
                 errmsg("string is too long for tsvector (%d bytes, max %d bytes)", dataoff, MAXSTRPOS)));

    /*
     * Adjust sizes (asserting that we didn't overrun the original estimates)
     * and collapse out any unused array entries.
     */
    output_size = ptr - ARRPTR(out);
    Assert(output_size <= out->size);
    out->size = output_size;
    if (data != STRPTR(out))
        memmove(STRPTR(out), data, dataoff);
    output_bytes = CALCDATASIZE(out->size, dataoff);
    Assert(output_bytes <= VARSIZE(out));
    SET_VARSIZE(out, output_bytes);

    PG_FREE_IF_COPY(in1, 0);
    PG_FREE_IF_COPY(in2, 1);
    PG_RETURN_POINTER(out);
}

/*
 * Compare two strings by tsvector rules.
 *
 * if prefix = true then it returns zero value iff b has prefix a
 */
int32
tsCompareString(char *a, int lena, char *b, int lenb, bool prefix)
{
    int         cmp;

    if (lena == 0)
    {
        if (prefix)
            cmp = 0;            /* empty string is prefix of anything */
        else
            cmp = (lenb > 0) ? -1 : 0;
    }
    else if (lenb == 0)
    {
        cmp = (lena > 0) ? 1 : 0;
    }
    else
    {
        cmp = memcmp(a, b, Min(lena, lenb));

        if (prefix)
        {
            if (cmp == 0 && lena > lenb)
                cmp = 1;        /* a is longer, so not a prefix of b */
        }
        else if (cmp == 0 && lena != lenb)
        {
            cmp = (lena < lenb) ? -1 : 1;
        }
    }

    return cmp;
}

/*
 * Check weight info or/and fill 'data' with the required positions
 */
static bool
checkclass_str(CHKVAL *chkval, WordEntry *entry, QueryOperand *val,
               ExecPhraseData *data)
{
    bool        result = false;

    if (entry->haspos && (val->weight || data))
    {
        WordEntryPosVector *posvec;

        /*
         * We can't use the _POSVECPTR macro here because the pointer to the
         * tsvector's lexeme storage is already contained in chkval->values.
         */
        posvec = (WordEntryPosVector *)
            (chkval->values + SHORTALIGN(entry->pos + entry->len));

        if (val->weight && data)
        {
            WordEntryPos *posvec_iter = posvec->pos;
            WordEntryPos *dptr;

            /*
             * Filter position information by weights
             */
            dptr = data->pos = palloc(sizeof(WordEntryPos) * posvec->npos);
            data->allocated = true;

            /* Is there a position with a matching weight? */
            while (posvec_iter < posvec->pos + posvec->npos)
            {
                /* If true, append this position to the data->pos */
                if (val->weight & (1 << WEP_GETWEIGHT(*posvec_iter)))
                {
                    *dptr = WEP_GETPOS(*posvec_iter);
                    dptr++;
                }

                posvec_iter++;
            }

            data->npos = dptr - data->pos;

            if (data->npos > 0)
                result = true;
        }
        else if (val->weight)
        {
            WordEntryPos *posvec_iter = posvec->pos;

            /* Is there a position with a matching weight? */
            while (posvec_iter < posvec->pos + posvec->npos)
            {
                if (val->weight & (1 << WEP_GETWEIGHT(*posvec_iter)))
                {
                    result = true;
                    break;      /* no need to go further */
                }

                posvec_iter++;
            }
        }
        else                    /* data != NULL */
        {
            data->npos = posvec->npos;
            data->pos = posvec->pos;
            data->allocated = false;
            result = true;
        }
    }
    else
    {
        result = true;
    }

    return result;
}

/*
 * is there value 'val' in array or not ?
 */
static bool
checkcondition_str(void *checkval, QueryOperand *val, ExecPhraseData *data)
{
    CHKVAL     *chkval = (CHKVAL *) checkval;
    WordEntry  *StopLow = chkval->arrb;
    WordEntry  *StopHigh = chkval->arre;
    WordEntry  *StopMiddle = StopHigh;
    bool        res = false;

    /* Loop invariant: StopLow <= val < StopHigh */
    while (StopLow < StopHigh)
    {
        int         difference;

        StopMiddle = StopLow + (StopHigh - StopLow) / 2;
        difference = tsCompareString(chkval->operand + val->distance,
                                     val->length,
                                     chkval->values + StopMiddle->pos,
                                     StopMiddle->len,
                                     false);

        if (difference == 0)
        {
            /* Check weight info & fill 'data' with positions */
            res = checkclass_str(chkval, StopMiddle, val, data);
            break;
        }
        else if (difference > 0)
            StopLow = StopMiddle + 1;
        else
            StopHigh = StopMiddle;
    }

    if ((!res || data) && val->prefix)
    {
        WordEntryPos *allpos = NULL;
        int         npos = 0,
                    totalpos = 0;

        /*
         * there was a failed exact search, so we should scan further to find
         * a prefix match. We also need to do so if caller needs position info
         */
        if (StopLow >= StopHigh)
            StopMiddle = StopHigh;

        while ((!res || data) && StopMiddle < chkval->arre &&
               tsCompareString(chkval->operand + val->distance,
                               val->length,
                               chkval->values + StopMiddle->pos,
                               StopMiddle->len,
                               true) == 0)
        {
            if (data)
            {
                /*
                 * We need to join position information
                 */
                res = checkclass_str(chkval, StopMiddle, val, data);

                if (res)
                {
                    while (npos + data->npos >= totalpos)
                    {
                        if (totalpos == 0)
                        {
                            totalpos = 256;
                            allpos = palloc(sizeof(WordEntryPos) * totalpos);
                        }
                        else
                        {
                            totalpos *= 2;
                            allpos = repalloc(allpos, sizeof(WordEntryPos) * totalpos);
                        }
                    }

                    memcpy(allpos + npos, data->pos, sizeof(WordEntryPos) * data->npos);
                    npos += data->npos;
                }
                else
                {
                    /* at loop exit, res must be true if we found matches */
                    res = (npos > 0);
                }
            }
            else
            {
                res = checkclass_str(chkval, StopMiddle, val, NULL);
            }

            StopMiddle++;
        }

        if (res && data)
        {
            /* Sort and make unique array of found positions */
            data->pos = allpos;
            qsort(data->pos, npos, sizeof(WordEntryPos), compareWordEntryPos);
            data->npos = qunique(data->pos, npos, sizeof(WordEntryPos),
                                 compareWordEntryPos);
            data->allocated = true;
        }
    }

    return res;
}

/*
 * Compute output position list for a tsquery operator in phrase mode.
 *
 * Merge the position lists in Ldata and Rdata as specified by "emit",
 * returning the result list into *data.  The input position lists must be
 * sorted and unique, and the output will be as well.
 *
 * data: pointer to initially-all-zeroes output struct, or NULL
 * Ldata, Rdata: input position lists
 * emit: bitmask of TSPO_XXX flags
 * Loffset: offset to be added to Ldata positions before comparing/outputting
 * Roffset: offset to be added to Rdata positions before comparing/outputting
 * max_npos: maximum possible required size of output position array
 *
 * Loffset and Roffset should not be negative, else we risk trying to output
 * negative positions, which won't fit into WordEntryPos.
 *
 * The result is boolean (TS_YES or TS_NO), but for the caller's convenience
 * we return it as TSTernaryValue.
 *
 * Returns TS_YES if any positions were emitted to *data; or if data is NULL,
 * returns TS_YES if any positions would have been emitted.
 */
#define TSPO_L_ONLY     0x01    /* emit positions appearing only in L */
#define TSPO_R_ONLY     0x02    /* emit positions appearing only in R */
#define TSPO_BOTH       0x04    /* emit positions appearing in both L&R */

static TSTernaryValue
TS_phrase_output(ExecPhraseData *data,
                 ExecPhraseData *Ldata,
                 ExecPhraseData *Rdata,
                 int emit,
                 int Loffset,
                 int Roffset,
                 int max_npos)
{
    int         Lindex,
                Rindex;

    /* Loop until both inputs are exhausted */
    Lindex = Rindex = 0;
    while (Lindex < Ldata->npos || Rindex < Rdata->npos)
    {
        int         Lpos,
                    Rpos;
        int         output_pos = 0;

        /*
         * Fetch current values to compare.  WEP_GETPOS() is needed because
         * ExecPhraseData->data can point to a tsvector's WordEntryPosVector.
         */
        if (Lindex < Ldata->npos)
            Lpos = WEP_GETPOS(Ldata->pos[Lindex]) + Loffset;
        else
        {
            /* L array exhausted, so we're done if R_ONLY isn't set */
            if (!(emit & TSPO_R_ONLY))
                break;
            Lpos = INT_MAX;
        }
        if (Rindex < Rdata->npos)
            Rpos = WEP_GETPOS(Rdata->pos[Rindex]) + Roffset;
        else
        {
            /* R array exhausted, so we're done if L_ONLY isn't set */
            if (!(emit & TSPO_L_ONLY))
                break;
            Rpos = INT_MAX;
        }

        /* Merge-join the two input lists */
        if (Lpos < Rpos)
        {
            /* Lpos is not matched in Rdata, should we output it? */
            if (emit & TSPO_L_ONLY)
                output_pos = Lpos;
            Lindex++;
        }
        else if (Lpos == Rpos)
        {
            /* Lpos and Rpos match ... should we output it? */
            if (emit & TSPO_BOTH)
                output_pos = Rpos;
            Lindex++;
            Rindex++;
        }
        else                    /* Lpos > Rpos */
        {
            /* Rpos is not matched in Ldata, should we output it? */
            if (emit & TSPO_R_ONLY)
                output_pos = Rpos;
            Rindex++;
        }

        if (output_pos > 0)
        {
            if (data)
            {
                /* Store position, first allocating output array if needed */
                if (data->pos == NULL)
                {
                    data->pos = (WordEntryPos *)
                        palloc(max_npos * sizeof(WordEntryPos));
                    data->allocated = true;
                }
                data->pos[data->npos++] = output_pos;
            }
            else
            {
                /*
                 * Exact positions not needed, so return TS_YES as soon as we
                 * know there is at least one.
                 */
                return TS_YES;
            }
        }
    }

    if (data && data->npos > 0)
    {
        /* Let's assert we didn't overrun the array */
        Assert(data->npos <= max_npos);
        return TS_YES;
    }
    return TS_NO;
}

/*
 * Execute tsquery at or below an OP_PHRASE operator.
 *
 * This handles tsquery execution at recursion levels where we need to care
 * about match locations.
 *
 * In addition to the same arguments used for TS_execute, the caller may pass
 * a preinitialized-to-zeroes ExecPhraseData struct, to be filled with lexeme
 * match position info on success.  data == NULL if no position data need be
 * returned.  (In practice, outside callers pass NULL, and only the internal
 * recursion cases pass a data pointer.)
 * Note: the function assumes data != NULL for operators other than OP_PHRASE.
 * This is OK because an outside call always starts from an OP_PHRASE node.
 *
 * The detailed semantics of the match data, given that the function returned
 * TS_YES (successful match), are:
 *
 * npos > 0, negate = false:
 *   query is matched at specified position(s) (and only those positions)
 * npos > 0, negate = true:
 *   query is matched at all positions *except* specified position(s)
 * npos = 0, negate = true:
 *   query is matched at all positions
 * npos = 0, negate = false:
 *   disallowed (this should result in TS_NO or TS_MAYBE, as appropriate)
 *
 * Successful matches also return a "width" value which is the match width in
 * lexemes, less one.  Hence, "width" is zero for simple one-lexeme matches,
 * and is the sum of the phrase operator distances for phrase matches.  Note
 * that when width > 0, the listed positions represent the ends of matches not
 * the starts.  (This unintuitive rule is needed to avoid possibly generating
 * negative positions, which wouldn't fit into the WordEntryPos arrays.)
 *
 * If the TSExecuteCallback function reports that an operand is present
 * but fails to provide position(s) for it, we will return TS_MAYBE when
 * it is possible but not certain that the query is matched.
 *
 * When the function returns TS_NO or TS_MAYBE, it must return npos = 0,
 * negate = false (which is the state initialized by the caller); but the
 * "width" output in such cases is undefined.
 */
static TSTernaryValue
TS_phrase_execute(QueryItem *curitem, void *arg, uint32 flags,
                  TSExecuteCallback chkcond,
                  ExecPhraseData *data)
{
    ExecPhraseData Ldata,
                Rdata;
    TSTernaryValue lmatch,
                rmatch;
    int         Loffset,
                Roffset,
                maxwidth;

    /* since this function recurses, it could be driven to stack overflow */
    check_stack_depth();

    if (curitem->type == QI_VAL)
    {
        if (!chkcond(arg, (QueryOperand *) curitem, data))
            return TS_NO;
        if (data->npos > 0 || data->negate)
            return TS_YES;
        /* If we have no position data, we must return TS_MAYBE */
        return TS_MAYBE;
    }

    switch (curitem->qoperator.oper)
    {
        case OP_NOT:

            /*
             * We need not touch data->width, since a NOT operation does not
             * change the match width.
             */
            if (!(flags & TS_EXEC_CALC_NOT))
            {
                /* without CALC_NOT, report NOT as "match everywhere" */
                Assert(data->npos == 0 && !data->negate);
                data->negate = true;
                return TS_YES;
            }
            switch (TS_phrase_execute(curitem + 1, arg, flags, chkcond, data))
            {
                case TS_NO:
                    /* change "match nowhere" to "match everywhere" */
                    Assert(data->npos == 0 && !data->negate);
                    data->negate = true;
                    return TS_YES;
                case TS_YES:
                    if (data->npos > 0)
                    {
                        /* we have some positions, invert negate flag */
                        data->negate = !data->negate;
                        return TS_YES;
                    }
                    else if (data->negate)
                    {
                        /* change "match everywhere" to "match nowhere" */
                        data->negate = false;
                        return TS_NO;
                    }
                    /* Should not get here if result was TS_YES */
                    Assert(false);
                    break;
                case TS_MAYBE:
                    /* match positions are, and remain, uncertain */
                    return TS_MAYBE;
            }
            break;

        case OP_PHRASE:
        case OP_AND:
            memset(&Ldata, 0, sizeof(Ldata));
            memset(&Rdata, 0, sizeof(Rdata));

            lmatch = TS_phrase_execute(curitem + curitem->qoperator.left,
                                       arg, flags, chkcond, &Ldata);
            if (lmatch == TS_NO)
                return TS_NO;

            rmatch = TS_phrase_execute(curitem + 1,
                                       arg, flags, chkcond, &Rdata);
            if (rmatch == TS_NO)
                return TS_NO;

            /*
             * If either operand has no position information, then we can't
             * return reliable position data, only a MAYBE result.
             */
            if (lmatch == TS_MAYBE || rmatch == TS_MAYBE)
                return TS_MAYBE;

            if (curitem->qoperator.oper == OP_PHRASE)
            {
                /*
                 * Compute Loffset and Roffset suitable for phrase match, and
                 * compute overall width of whole phrase match.
                 */
                Loffset = curitem->qoperator.distance + Rdata.width;
                Roffset = 0;
                if (data)
                    data->width = curitem->qoperator.distance +
                        Ldata.width + Rdata.width;
            }
            else
            {
                /*
                 * For OP_AND, set output width and alignment like OP_OR (see
                 * comment below)
                 */
                maxwidth = Max(Ldata.width, Rdata.width);
                Loffset = maxwidth - Ldata.width;
                Roffset = maxwidth - Rdata.width;
                if (data)
                    data->width = maxwidth;
            }

            if (Ldata.negate && Rdata.negate)
            {
                /* !L & !R: treat as !(L | R) */
                (void) TS_phrase_output(data, &Ldata, &Rdata,
                                        TSPO_BOTH | TSPO_L_ONLY | TSPO_R_ONLY,
                                        Loffset, Roffset,
                                        Ldata.npos + Rdata.npos);
                if (data)
                    data->negate = true;
                return TS_YES;
            }
            else if (Ldata.negate)
            {
                /* !L & R */
                return TS_phrase_output(data, &Ldata, &Rdata,
                                        TSPO_R_ONLY,
                                        Loffset, Roffset,
                                        Rdata.npos);
            }
            else if (Rdata.negate)
            {
                /* L & !R */
                return TS_phrase_output(data, &Ldata, &Rdata,
                                        TSPO_L_ONLY,
                                        Loffset, Roffset,
                                        Ldata.npos);
            }
            else
            {
                /* straight AND */
                return TS_phrase_output(data, &Ldata, &Rdata,
                                        TSPO_BOTH,
                                        Loffset, Roffset,
                                        Min(Ldata.npos, Rdata.npos));
            }

        case OP_OR:
            memset(&Ldata, 0, sizeof(Ldata));
            memset(&Rdata, 0, sizeof(Rdata));

            lmatch = TS_phrase_execute(curitem + curitem->qoperator.left,
                                       arg, flags, chkcond, &Ldata);
            rmatch = TS_phrase_execute(curitem + 1,
                                       arg, flags, chkcond, &Rdata);

            if (lmatch == TS_NO && rmatch == TS_NO)
                return TS_NO;

            /*
             * If either operand has no position information, then we can't
             * return reliable position data, only a MAYBE result.
             */
            if (lmatch == TS_MAYBE || rmatch == TS_MAYBE)
                return TS_MAYBE;

            /*
             * Cope with undefined output width from failed submatch.  (This
             * takes less code than trying to ensure that all failure returns
             * set data->width to zero.)
             */
            if (lmatch == TS_NO)
                Ldata.width = 0;
            if (rmatch == TS_NO)
                Rdata.width = 0;

            /*
             * For OP_AND and OP_OR, report the width of the wider of the two
             * inputs, and align the narrower input's positions to the right
             * end of that width.  This rule deals at least somewhat
             * reasonably with cases like "x <-> (y | z <-> q)".
             */
            maxwidth = Max(Ldata.width, Rdata.width);
            Loffset = maxwidth - Ldata.width;
            Roffset = maxwidth - Rdata.width;
            data->width = maxwidth;

            if (Ldata.negate && Rdata.negate)
            {
                /* !L | !R: treat as !(L & R) */
                (void) TS_phrase_output(data, &Ldata, &Rdata,
                                        TSPO_BOTH,
                                        Loffset, Roffset,
                                        Min(Ldata.npos, Rdata.npos));
                data->negate = true;
                return TS_YES;
            }
            else if (Ldata.negate)
            {
                /* !L | R: treat as !(L & !R) */
                (void) TS_phrase_output(data, &Ldata, &Rdata,
                                        TSPO_L_ONLY,
                                        Loffset, Roffset,
                                        Ldata.npos);
                data->negate = true;
                return TS_YES;
            }
            else if (Rdata.negate)
            {
                /* L | !R: treat as !(!L & R) */
                (void) TS_phrase_output(data, &Ldata, &Rdata,
                                        TSPO_R_ONLY,
                                        Loffset, Roffset,
                                        Rdata.npos);
                data->negate = true;
                return TS_YES;
            }
            else
            {
                /* straight OR */
                return TS_phrase_output(data, &Ldata, &Rdata,
                                        TSPO_BOTH | TSPO_L_ONLY | TSPO_R_ONLY,
                                        Loffset, Roffset,
                                        Ldata.npos + Rdata.npos);
            }

        default:
            elog(ERROR, "unrecognized operator: %d", curitem->qoperator.oper);
    }

    /* not reachable, but keep compiler quiet */
    return TS_NO;
}


/*
 * Evaluate tsquery boolean expression.
 *
 * curitem: current tsquery item (initially, the first one)
 * arg: opaque value to pass through to callback function
 * flags: bitmask of flag bits shown in ts_utils.h
 * chkcond: callback function to check whether a primitive value is present
 */
bool
TS_execute(QueryItem *curitem, void *arg, uint32 flags,
           TSExecuteCallback chkcond)
{
    /*
     * If we get TS_MAYBE from the recursion, return true.  We could only see
     * that result if the caller passed TS_EXEC_PHRASE_NO_POS, so there's no
     * need to check again.
     */
    return TS_execute_recurse(curitem, arg, flags, chkcond) != TS_NO;
}

/*
 * TS_execute recursion for operators above any phrase operator.  Here we do
 * not need to worry about lexeme positions.  As soon as we hit an OP_PHRASE
 * operator, we pass it off to TS_phrase_execute which does worry.
 */
static TSTernaryValue
TS_execute_recurse(QueryItem *curitem, void *arg, uint32 flags,
                   TSExecuteCallback chkcond)
{
    TSTernaryValue lmatch;

    /* since this function recurses, it could be driven to stack overflow */
    check_stack_depth();

    if (curitem->type == QI_VAL)
        return chkcond(arg, (QueryOperand *) curitem,
                       NULL /* don't need position info */ ) ? TS_YES : TS_NO;

    switch (curitem->qoperator.oper)
    {
        case OP_NOT:
            if (!(flags & TS_EXEC_CALC_NOT))
                return TS_YES;
            switch (TS_execute_recurse(curitem + 1, arg, flags, chkcond))
            {
                case TS_NO:
                    return TS_YES;
                case TS_YES:
                    return TS_NO;
                case TS_MAYBE:
                    return TS_MAYBE;
            }
            break;

        case OP_AND:
            lmatch = TS_execute_recurse(curitem + curitem->qoperator.left, arg,
                                        flags, chkcond);
            if (lmatch == TS_NO)
                return TS_NO;
            switch (TS_execute_recurse(curitem + 1, arg, flags, chkcond))
            {
                case TS_NO:
                    return TS_NO;
                case TS_YES:
                    return lmatch;
                case TS_MAYBE:
                    return TS_MAYBE;
            }
            break;

        case OP_OR:
            lmatch = TS_execute_recurse(curitem + curitem->qoperator.left, arg,
                                        flags, chkcond);
            if (lmatch == TS_YES)
                return TS_YES;
            switch (TS_execute_recurse(curitem + 1, arg, flags, chkcond))
            {
                case TS_NO:
                    return lmatch;
                case TS_YES:
                    return TS_YES;
                case TS_MAYBE:
                    return TS_MAYBE;
            }
            break;

        case OP_PHRASE:

            /*
             * If we get a MAYBE result, and the caller doesn't want that,
             * convert it to NO.  It would be more consistent, perhaps, to
             * return the result of TS_phrase_execute() verbatim and then
             * convert MAYBE results at the top of the recursion.  But
             * converting at the topmost phrase operator gives results that
             * are bug-compatible with the old implementation, so do it like
             * this for now.
             */
            switch (TS_phrase_execute(curitem, arg, flags, chkcond, NULL))
            {
                case TS_NO:
                    return TS_NO;
                case TS_YES:
                    return TS_YES;
                case TS_MAYBE:
                    return (flags & TS_EXEC_PHRASE_NO_POS) ? TS_MAYBE : TS_NO;
            }
            break;

        default:
            elog(ERROR, "unrecognized operator: %d", curitem->qoperator.oper);
    }

    /* not reachable, but keep compiler quiet */
    return TS_NO;
}

/*
 * Detect whether a tsquery boolean expression requires any positive matches
 * to values shown in the tsquery.
 *
 * This is needed to know whether a GIN index search requires full index scan.
 * For example, 'x & !y' requires a match of x, so it's sufficient to scan
 * entries for x; but 'x | !y' could match rows containing neither x nor y.
 */
bool
tsquery_requires_match(QueryItem *curitem)
{
    /* since this function recurses, it could be driven to stack overflow */
    check_stack_depth();

    if (curitem->type == QI_VAL)
        return true;

    switch (curitem->qoperator.oper)
    {
        case OP_NOT:

            /*
             * Assume there are no required matches underneath a NOT.  For
             * some cases with nested NOTs, we could prove there's a required
             * match, but it seems unlikely to be worth the trouble.
             */
            return false;

        case OP_PHRASE:

            /*
             * Treat OP_PHRASE as OP_AND here
             */
        case OP_AND:
            /* If either side requires a match, we're good */
            if (tsquery_requires_match(curitem + curitem->qoperator.left))
                return true;
            else
                return tsquery_requires_match(curitem + 1);

        case OP_OR:
            /* Both sides must require a match */
            if (tsquery_requires_match(curitem + curitem->qoperator.left))
                return tsquery_requires_match(curitem + 1);
            else
                return false;

        default:
            elog(ERROR, "unrecognized operator: %d", curitem->qoperator.oper);
    }

    /* not reachable, but keep compiler quiet */
    return false;
}

/*
 * boolean operations
 */
Datum
ts_match_qv(PG_FUNCTION_ARGS)
{
    PG_RETURN_DATUM(DirectFunctionCall2(ts_match_vq,
                                        PG_GETARG_DATUM(1),
                                        PG_GETARG_DATUM(0)));
}

Datum
ts_match_vq(PG_FUNCTION_ARGS)
{
    TSVector    val = PG_GETARG_TSVECTOR(0);
    TSQuery     query = PG_GETARG_TSQUERY(1);
    CHKVAL      chkval;
    bool        result;

    /* empty query matches nothing */
    if (!query->size)
    {
        PG_FREE_IF_COPY(val, 0);
        PG_FREE_IF_COPY(query, 1);
        PG_RETURN_BOOL(false);
    }

    chkval.arrb = ARRPTR(val);
    chkval.arre = chkval.arrb + val->size;
    chkval.values = STRPTR(val);
    chkval.operand = GETOPERAND(query);
    result = TS_execute(GETQUERY(query),
                        &chkval,
                        TS_EXEC_CALC_NOT,
                        checkcondition_str);

    PG_FREE_IF_COPY(val, 0);
    PG_FREE_IF_COPY(query, 1);
    PG_RETURN_BOOL(result);
}

Datum
ts_match_tt(PG_FUNCTION_ARGS)
{
    TSVector    vector;
    TSQuery     query;
    bool        res;

    vector = DatumGetTSVector(DirectFunctionCall1(to_tsvector,
                                                  PG_GETARG_DATUM(0)));
    query = DatumGetTSQuery(DirectFunctionCall1(plainto_tsquery,
                                                PG_GETARG_DATUM(1)));

    res = DatumGetBool(DirectFunctionCall2(ts_match_vq,
                                           TSVectorGetDatum(vector),
                                           TSQueryGetDatum(query)));

    pfree(vector);
    pfree(query);

    PG_RETURN_BOOL(res);
}

Datum
ts_match_tq(PG_FUNCTION_ARGS)
{
    TSVector    vector;
    TSQuery     query = PG_GETARG_TSQUERY(1);
    bool        res;

    vector = DatumGetTSVector(DirectFunctionCall1(to_tsvector,
                                                  PG_GETARG_DATUM(0)));

    res = DatumGetBool(DirectFunctionCall2(ts_match_vq,
                                           TSVectorGetDatum(vector),
                                           TSQueryGetDatum(query)));

    pfree(vector);
    PG_FREE_IF_COPY(query, 1);

    PG_RETURN_BOOL(res);
}

/*
 * ts_stat statistic function support
 */


/*
 * Returns the number of positions in value 'wptr' within tsvector 'txt',
 * that have a weight equal to one of the weights in 'weight' bitmask.
 */
static int
check_weight(TSVector txt, WordEntry *wptr, int8 weight)
{
    int         len = POSDATALEN(txt, wptr);
    int         num = 0;
    WordEntryPos *ptr = POSDATAPTR(txt, wptr);

    while (len--)
    {
        if (weight & (1 << WEP_GETWEIGHT(*ptr)))
            num++;
        ptr++;
    }
    return num;
}

#define compareStatWord(a,e,t)                          \
    tsCompareString((a)->lexeme, (a)->lenlexeme,        \
                    STRPTR(t) + (e)->pos, (e)->len,     \
                    false)

static void
insertStatEntry(MemoryContext persistentContext, TSVectorStat *stat, TSVector txt, uint32 off)
{
    WordEntry  *we = ARRPTR(txt) + off;
    StatEntry  *node = stat->root,
               *pnode = NULL;
    int         n,
                res = 0;
    uint32      depth = 1;

    if (stat->weight == 0)
        n = (we->haspos) ? POSDATALEN(txt, we) : 1;
    else
        n = (we->haspos) ? check_weight(txt, we, stat->weight) : 0;

    if (n == 0)
        return;                 /* nothing to insert */

    while (node)
    {
        res = compareStatWord(node, we, txt);

        if (res == 0)
        {
            break;
        }
        else
        {
            pnode = node;
            node = (res < 0) ? node->left : node->right;
        }
        depth++;
    }

    if (depth > stat->maxdepth)
        stat->maxdepth = depth;

    if (node == NULL)
    {
        node = MemoryContextAlloc(persistentContext, STATENTRYHDRSZ + we->len);
        node->left = node->right = NULL;
        node->ndoc = 1;
        node->nentry = n;
        node->lenlexeme = we->len;
        memcpy(node->lexeme, STRPTR(txt) + we->pos, node->lenlexeme);

        if (pnode == NULL)
        {
            stat->root = node;
        }
        else
        {
            if (res < 0)
                pnode->left = node;
            else
                pnode->right = node;
        }

    }
    else
    {
        node->ndoc++;
        node->nentry += n;
    }
}

static void
chooseNextStatEntry(MemoryContext persistentContext, TSVectorStat *stat, TSVector txt,
                    uint32 low, uint32 high, uint32 offset)
{
    uint32      pos;
    uint32      middle = (low + high) >> 1;

    pos = (low + middle) >> 1;
    if (low != middle && pos >= offset && pos - offset < txt->size)
        insertStatEntry(persistentContext, stat, txt, pos - offset);
    pos = (high + middle + 1) >> 1;
    if (middle + 1 != high && pos >= offset && pos - offset < txt->size)
        insertStatEntry(persistentContext, stat, txt, pos - offset);

    if (low != middle)
        chooseNextStatEntry(persistentContext, stat, txt, low, middle, offset);
    if (high != middle + 1)
        chooseNextStatEntry(persistentContext, stat, txt, middle + 1, high, offset);
}

/*
 * This is written like a custom aggregate function, because the
 * original plan was to do just that. Unfortunately, an aggregate function
 * can't return a set, so that plan was abandoned. If that limitation is
 * lifted in the future, ts_stat could be a real aggregate function so that
 * you could use it like this:
 *
 *   SELECT ts_stat(vector_column) FROM vector_table;
 *
 *  where vector_column is a tsvector-type column in vector_table.
 */

static TSVectorStat *
ts_accum(MemoryContext persistentContext, TSVectorStat *stat, Datum data)
{
    TSVector    txt = DatumGetTSVector(data);
    uint32      i,
                nbit = 0,
                offset;

    if (stat == NULL)
    {                           /* Init in first */
        stat = MemoryContextAllocZero(persistentContext, sizeof(TSVectorStat));
        stat->maxdepth = 1;
    }

    /* simple check of correctness */
    if (txt == NULL || txt->size == 0)
    {
        if (txt && txt != (TSVector) DatumGetPointer(data))
            pfree(txt);
        return stat;
    }

    i = txt->size - 1;
    for (; i > 0; i >>= 1)
        nbit++;

    nbit = 1 << nbit;
    offset = (nbit - txt->size) / 2;

    insertStatEntry(persistentContext, stat, txt, (nbit >> 1) - offset);
    chooseNextStatEntry(persistentContext, stat, txt, 0, nbit, offset);

    return stat;
}

static void
ts_setup_firstcall(FunctionCallInfo fcinfo, FuncCallContext *funcctx,
                   TSVectorStat *stat)
{
    TupleDesc   tupdesc;
    MemoryContext oldcontext;
    StatEntry  *node;

    funcctx->user_fctx = (void *) stat;

    oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);

    stat->stack = palloc0(sizeof(StatEntry *) * (stat->maxdepth + 1));
    stat->stackpos = 0;

    node = stat->root;
    /* find leftmost value */
    if (node == NULL)
        stat->stack[stat->stackpos] = NULL;
    else
        for (;;)
        {
            stat->stack[stat->stackpos] = node;
            if (node->left)
            {
                stat->stackpos++;
                node = node->left;
            }
            else
                break;
        }
    Assert(stat->stackpos <= stat->maxdepth);

    tupdesc = CreateTemplateTupleDesc(3);
    TupleDescInitEntry(tupdesc, (AttrNumber) 1, "word",
                       TEXTOID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 2, "ndoc",
                       INT4OID, -1, 0);
    TupleDescInitEntry(tupdesc, (AttrNumber) 3, "nentry",
                       INT4OID, -1, 0);
    funcctx->tuple_desc = BlessTupleDesc(tupdesc);
    funcctx->attinmeta = TupleDescGetAttInMetadata(tupdesc);

    MemoryContextSwitchTo(oldcontext);
}

static StatEntry *
walkStatEntryTree(TSVectorStat *stat)
{
    StatEntry  *node = stat->stack[stat->stackpos];

    if (node == NULL)
        return NULL;

    if (node->ndoc != 0)
    {
        /* return entry itself: we already was at left sublink */
        return node;
    }
    else if (node->right && node->right != stat->stack[stat->stackpos + 1])
    {
        /* go on right sublink */
        stat->stackpos++;
        node = node->right;

        /* find most-left value */
        for (;;)
        {
            stat->stack[stat->stackpos] = node;
            if (node->left)
            {
                stat->stackpos++;
                node = node->left;
            }
            else
                break;
        }
        Assert(stat->stackpos <= stat->maxdepth);
    }
    else
    {
        /* we already return all left subtree, itself and  right subtree */
        if (stat->stackpos == 0)
            return NULL;

        stat->stackpos--;
        return walkStatEntryTree(stat);
    }

    return node;
}

static Datum
ts_process_call(FuncCallContext *funcctx)
{
    TSVectorStat *st;
    StatEntry  *entry;

    st = (TSVectorStat *) funcctx->user_fctx;

    entry = walkStatEntryTree(st);

    if (entry != NULL)
    {
        Datum       result;
        char       *values[3];
        char        ndoc[16];
        char        nentry[16];
        HeapTuple   tuple;

        values[0] = palloc(entry->lenlexeme + 1);
        memcpy(values[0], entry->lexeme, entry->lenlexeme);
        (values[0])[entry->lenlexeme] = '\0';
        sprintf(ndoc, "%d", entry->ndoc);
        values[1] = ndoc;
        sprintf(nentry, "%d", entry->nentry);
        values[2] = nentry;

        tuple = BuildTupleFromCStrings(funcctx->attinmeta, values);
        result = HeapTupleGetDatum(tuple);

        pfree(values[0]);

        /* mark entry as already visited */
        entry->ndoc = 0;

        return result;
    }

    return (Datum) 0;
}

static TSVectorStat *
ts_stat_sql(MemoryContext persistentContext, text *txt, text *ws)
{
    char       *query = text_to_cstring(txt);
    TSVectorStat *stat;
    bool        isnull;
    Portal      portal;
    SPIPlanPtr  plan;

    if ((plan = SPI_prepare(query, 0, NULL)) == NULL)
        /* internal error */
        elog(ERROR, "SPI_prepare(\"%s\") failed", query);

    if ((portal = SPI_cursor_open(NULL, plan, NULL, NULL, true)) == NULL)
        /* internal error */
        elog(ERROR, "SPI_cursor_open(\"%s\") failed", query);

    SPI_cursor_fetch(portal, true, 100);

    if (SPI_tuptable == NULL ||
        SPI_tuptable->tupdesc->natts != 1 ||
        !IsBinaryCoercible(SPI_gettypeid(SPI_tuptable->tupdesc, 1),
                           TSVECTOROID))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                 errmsg("ts_stat query must return one tsvector column")));

    stat = MemoryContextAllocZero(persistentContext, sizeof(TSVectorStat));
    stat->maxdepth = 1;

    if (ws)
    {
        char       *buf;

        buf = VARDATA_ANY(ws);
        while (buf - VARDATA_ANY(ws) < VARSIZE_ANY_EXHDR(ws))
        {
            if (pg_mblen(buf) == 1)
            {
                switch (*buf)
                {
                    case 'A':
                    case 'a':
                        stat->weight |= 1 << 3;
                        break;
                    case 'B':
                    case 'b':
                        stat->weight |= 1 << 2;
                        break;
                    case 'C':
                    case 'c':
                        stat->weight |= 1 << 1;
                        break;
                    case 'D':
                    case 'd':
                        stat->weight |= 1;
                        break;
                    default:
                        stat->weight |= 0;
                }
            }
            buf += pg_mblen(buf);
        }
    }

    while (SPI_processed > 0)
    {
        uint64      i;

        for (i = 0; i < SPI_processed; i++)
        {
            Datum       data = SPI_getbinval(SPI_tuptable->vals[i], SPI_tuptable->tupdesc, 1, &isnull);

            if (!isnull)
                stat = ts_accum(persistentContext, stat, data);
        }

        SPI_freetuptable(SPI_tuptable);
        SPI_cursor_fetch(portal, true, 100);
    }

    SPI_freetuptable(SPI_tuptable);
    SPI_cursor_close(portal);
    SPI_freeplan(plan);
    pfree(query);

    return stat;
}

Datum
ts_stat1(PG_FUNCTION_ARGS)
{
    FuncCallContext *funcctx;
    Datum       result;

    if (SRF_IS_FIRSTCALL())
    {
        TSVectorStat *stat;
        text       *txt = PG_GETARG_TEXT_PP(0);

        funcctx = SRF_FIRSTCALL_INIT();
        SPI_connect();
        stat = ts_stat_sql(funcctx->multi_call_memory_ctx, txt, NULL);
        PG_FREE_IF_COPY(txt, 0);
        ts_setup_firstcall(fcinfo, funcctx, stat);
        SPI_finish();
    }

    funcctx = SRF_PERCALL_SETUP();
    if ((result = ts_process_call(funcctx)) != (Datum) 0)
        SRF_RETURN_NEXT(funcctx, result);
    SRF_RETURN_DONE(funcctx);
}

Datum
ts_stat2(PG_FUNCTION_ARGS)
{
    FuncCallContext *funcctx;
    Datum       result;

    if (SRF_IS_FIRSTCALL())
    {
        TSVectorStat *stat;
        text       *txt = PG_GETARG_TEXT_PP(0);
        text       *ws = PG_GETARG_TEXT_PP(1);

        funcctx = SRF_FIRSTCALL_INIT();
        SPI_connect();
        stat = ts_stat_sql(funcctx->multi_call_memory_ctx, txt, ws);
        PG_FREE_IF_COPY(txt, 0);
        PG_FREE_IF_COPY(ws, 1);
        ts_setup_firstcall(fcinfo, funcctx, stat);
        SPI_finish();
    }

    funcctx = SRF_PERCALL_SETUP();
    if ((result = ts_process_call(funcctx)) != (Datum) 0)
        SRF_RETURN_NEXT(funcctx, result);
    SRF_RETURN_DONE(funcctx);
}


/*
 * Triggers for automatic update of a tsvector column from text column(s)
 *
 * Trigger arguments are either
 *      name of tsvector col, name of tsconfig to use, name(s) of text col(s)
 *      name of tsvector col, name of regconfig col, name(s) of text col(s)
 * ie, tsconfig can either be specified by name, or indirectly as the
 * contents of a regconfig field in the row.  If the name is used, it must
 * be explicitly schema-qualified.
 */
Datum
tsvector_update_trigger_byid(PG_FUNCTION_ARGS)
{
    return tsvector_update_trigger(fcinfo, false);
}

Datum
tsvector_update_trigger_bycolumn(PG_FUNCTION_ARGS)
{
    return tsvector_update_trigger(fcinfo, true);
}

static Datum
tsvector_update_trigger(PG_FUNCTION_ARGS, bool config_column)
{
    TriggerData *trigdata;
    Trigger    *trigger;
    Relation    rel;
    HeapTuple   rettuple = NULL;
    int         tsvector_attr_num,
                i;
    ParsedText  prs;
    Datum       datum;
    bool        isnull;
    text       *txt;
    Oid         cfgId;
    bool        update_needed;

    /* Check call context */
    if (!CALLED_AS_TRIGGER(fcinfo)) /* internal error */
        elog(ERROR, "tsvector_update_trigger: not fired by trigger manager");

    trigdata = (TriggerData *) fcinfo->context;
    if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
        elog(ERROR, "tsvector_update_trigger: must be fired for row");
    if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
        elog(ERROR, "tsvector_update_trigger: must be fired BEFORE event");

    if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
    {
        rettuple = trigdata->tg_trigtuple;
        update_needed = true;
    }
    else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
    {
        rettuple = trigdata->tg_newtuple;
        update_needed = false;  /* computed below */
    }
    else
        elog(ERROR, "tsvector_update_trigger: must be fired for INSERT or UPDATE");

    trigger = trigdata->tg_trigger;
    rel = trigdata->tg_relation;

    if (trigger->tgnargs < 3)
        elog(ERROR, "tsvector_update_trigger: arguments must be tsvector_field, ts_config, text_field1, ...)");

    /* Find the target tsvector column */
    tsvector_attr_num = SPI_fnumber(rel->rd_att, trigger->tgargs[0]);
    if (tsvector_attr_num == SPI_ERROR_NOATTRIBUTE)
        ereport(ERROR,
                (errcode(ERRCODE_UNDEFINED_COLUMN),
                 errmsg("tsvector column \"%s\" does not exist",
                        trigger->tgargs[0])));
    /* This will effectively reject system columns, so no separate test: */
    if (!IsBinaryCoercible(SPI_gettypeid(rel->rd_att, tsvector_attr_num),
                           TSVECTOROID))
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("column \"%s\" is not of tsvector type",
                        trigger->tgargs[0])));

    /* Find the configuration to use */
    if (config_column)
    {
        int         config_attr_num;

        config_attr_num = SPI_fnumber(rel->rd_att, trigger->tgargs[1]);
        if (config_attr_num == SPI_ERROR_NOATTRIBUTE)
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("configuration column \"%s\" does not exist",
                            trigger->tgargs[1])));
        if (!IsBinaryCoercible(SPI_gettypeid(rel->rd_att, config_attr_num),
                               REGCONFIGOID))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("column \"%s\" is not of regconfig type",
                            trigger->tgargs[1])));

        datum = SPI_getbinval(rettuple, rel->rd_att, config_attr_num, &isnull);
        if (isnull)
            ereport(ERROR,
                    (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                     errmsg("configuration column \"%s\" must not be null",
                            trigger->tgargs[1])));
        cfgId = DatumGetObjectId(datum);
    }
    else
    {
        List       *names;

        names = stringToQualifiedNameList(trigger->tgargs[1]);
        /* require a schema so that results are not search path dependent */
        if (list_length(names) < 2)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                     errmsg("text search configuration name \"%s\" must be schema-qualified",
                            trigger->tgargs[1])));
        cfgId = get_ts_config_oid(names, false);
    }

    /* initialize parse state */
    prs.lenwords = 32;
    prs.curwords = 0;
    prs.pos = 0;
    prs.words = (ParsedWord *) palloc(sizeof(ParsedWord) * prs.lenwords);

    /* find all words in indexable column(s) */
    for (i = 2; i < trigger->tgnargs; i++)
    {
        int         numattr;

        numattr = SPI_fnumber(rel->rd_att, trigger->tgargs[i]);
        if (numattr == SPI_ERROR_NOATTRIBUTE)
            ereport(ERROR,
                    (errcode(ERRCODE_UNDEFINED_COLUMN),
                     errmsg("column \"%s\" does not exist",
                            trigger->tgargs[i])));
        if (!IsBinaryCoercible(SPI_gettypeid(rel->rd_att, numattr), TEXTOID))
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("column \"%s\" is not of a character type",
                            trigger->tgargs[i])));

        if (bms_is_member(numattr - FirstLowInvalidHeapAttributeNumber, trigdata->tg_updatedcols))
            update_needed = true;

        datum = SPI_getbinval(rettuple, rel->rd_att, numattr, &isnull);
        if (isnull)
            continue;

        txt = DatumGetTextPP(datum);

        parsetext(cfgId, &prs, VARDATA_ANY(txt), VARSIZE_ANY_EXHDR(txt));

        if (txt != (text *) DatumGetPointer(datum))
            pfree(txt);
    }

    if (update_needed)
    {
        /* make tsvector value */
        datum = TSVectorGetDatum(make_tsvector(&prs));
        isnull = false;

        /* and insert it into tuple */
        rettuple = heap_modify_tuple_by_cols(rettuple, rel->rd_att,
                                             1, &tsvector_attr_num,
                                             &datum, &isnull);

        pfree(DatumGetPointer(datum));
    }

    return PointerGetDatum(rettuple);
}