tsgistidx.c

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/*-------------------------------------------------------------------------
 *
 * tsgistidx.c
 *    GiST support functions for tsvector_ops
 *
 * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *    src/backend/utils/adt/tsgistidx.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/gist.h"
#include "access/heaptoast.h"
#include "lib/qunique.h"
#include "port/pg_bitutils.h"
#include "tsearch/ts_utils.h"
#include "utils/builtins.h"
#include "utils/pg_crc.h"


#define SIGLENINT  31           /* >121 => key will toast, so it will not work
                                 * !!! */

#define SIGLEN  ( sizeof(int32) * SIGLENINT )
#define SIGLENBIT (SIGLEN * BITS_PER_BYTE)

typedef char BITVEC[SIGLEN];
typedef char *BITVECP;

#define LOOPBYTE \
            for(i=0;i<SIGLEN;i++)

#define GETBYTE(x,i) ( *( (BITVECP)(x) + (int)( (i) / BITS_PER_BYTE ) ) )
#define GETBITBYTE(x,i) ( ((char)(x)) >> (i) & 0x01 )
#define CLRBIT(x,i)   GETBYTE(x,i) &= ~( 0x01 << ( (i) % BITS_PER_BYTE ) )
#define SETBIT(x,i)   GETBYTE(x,i) |=  ( 0x01 << ( (i) % BITS_PER_BYTE ) )
#define GETBIT(x,i) ( (GETBYTE(x,i) >> ( (i) % BITS_PER_BYTE )) & 0x01 )

#define HASHVAL(val) (((unsigned int)(val)) % SIGLENBIT)
#define HASH(sign, val) SETBIT((sign), HASHVAL(val))

#define GETENTRY(vec,pos) ((SignTSVector *) DatumGetPointer((vec)->vector[(pos)].key))

/*
 * type of GiST index key
 */

typedef struct
{
    int32       vl_len_;        /* varlena header (do not touch directly!) */
    int32       flag;
    char        data[FLEXIBLE_ARRAY_MEMBER];
} SignTSVector;

#define ARRKEY      0x01
#define SIGNKEY     0x02
#define ALLISTRUE   0x04

#define ISARRKEY(x) ( ((SignTSVector*)(x))->flag & ARRKEY )
#define ISSIGNKEY(x)    ( ((SignTSVector*)(x))->flag & SIGNKEY )
#define ISALLTRUE(x)    ( ((SignTSVector*)(x))->flag & ALLISTRUE )

#define GTHDRSIZE   ( VARHDRSZ + sizeof(int32) )
#define CALCGTSIZE(flag, len) ( GTHDRSIZE + ( ( (flag) & ARRKEY ) ? ((len)*sizeof(int32)) : (((flag) & ALLISTRUE) ? 0 : SIGLEN) ) )

#define GETSIGN(x)  ( (BITVECP)( (char*)(x)+GTHDRSIZE ) )
#define GETARR(x)   ( (int32*)( (char*)(x)+GTHDRSIZE ) )
#define ARRNELEM(x) ( ( VARSIZE(x) - GTHDRSIZE )/sizeof(int32) )

static int32 sizebitvec(BITVECP sign);

Datum
gtsvectorin(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("gtsvector_in not implemented")));
    PG_RETURN_DATUM(0);
}

#define SINGOUTSTR  "%d true bits, %d false bits"
#define ARROUTSTR   "%d unique words"
#define EXTRALEN    ( 2*13 )

static int  outbuf_maxlen = 0;

Datum
gtsvectorout(PG_FUNCTION_ARGS)
{
    SignTSVector *key = (SignTSVector *) PG_DETOAST_DATUM(PG_GETARG_POINTER(0));
    char       *outbuf;

    if (outbuf_maxlen == 0)
        outbuf_maxlen = 2 * EXTRALEN + Max(strlen(SINGOUTSTR), strlen(ARROUTSTR)) + 1;
    outbuf = palloc(outbuf_maxlen);

    if (ISARRKEY(key))
        sprintf(outbuf, ARROUTSTR, (int) ARRNELEM(key));
    else
    {
        int         cnttrue = (ISALLTRUE(key)) ? SIGLENBIT : sizebitvec(GETSIGN(key));

        sprintf(outbuf, SINGOUTSTR, cnttrue, (int) SIGLENBIT - cnttrue);
    }

    PG_FREE_IF_COPY(key, 0);
    PG_RETURN_POINTER(outbuf);
}

static int
compareint(const void *va, const void *vb)
{
    int32       a = *((const int32 *) va);
    int32       b = *((const int32 *) vb);

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

static void
makesign(BITVECP sign, SignTSVector *a)
{
    int32       k,
                len = ARRNELEM(a);
    int32      *ptr = GETARR(a);

    MemSet((void *) sign, 0, sizeof(BITVEC));
    for (k = 0; k < len; k++)
        HASH(sign, ptr[k]);
}

Datum
gtsvector_compress(PG_FUNCTION_ARGS)
{
    GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
    GISTENTRY  *retval = entry;

    if (entry->leafkey)
    {                           /* tsvector */
        SignTSVector *res;
        TSVector    val = DatumGetTSVector(entry->key);
        int32       len;
        int32      *arr;
        WordEntry  *ptr = ARRPTR(val);
        char       *words = STRPTR(val);

        len = CALCGTSIZE(ARRKEY, val->size);
        res = (SignTSVector *) palloc(len);
        SET_VARSIZE(res, len);
        res->flag = ARRKEY;
        arr = GETARR(res);
        len = val->size;
        while (len--)
        {
            pg_crc32    c;

            INIT_LEGACY_CRC32(c);
            COMP_LEGACY_CRC32(c, words + ptr->pos, ptr->len);
            FIN_LEGACY_CRC32(c);

            *arr = *(int32 *) &c;
            arr++;
            ptr++;
        }

        qsort(GETARR(res), val->size, sizeof(int), compareint);
        len = qunique(GETARR(res), val->size, sizeof(int), compareint);
        if (len != val->size)
        {
            /*
             * there is a collision of hash-function; len is always less than
             * val->size
             */
            len = CALCGTSIZE(ARRKEY, len);
            res = (SignTSVector *) repalloc((void *) res, len);
            SET_VARSIZE(res, len);
        }

        /* make signature, if array is too long */
        if (VARSIZE(res) > TOAST_INDEX_TARGET)
        {
            SignTSVector *ressign;

            len = CALCGTSIZE(SIGNKEY, 0);
            ressign = (SignTSVector *) palloc(len);
            SET_VARSIZE(ressign, len);
            ressign->flag = SIGNKEY;
            makesign(GETSIGN(ressign), res);
            res = ressign;
        }

        retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));
        gistentryinit(*retval, PointerGetDatum(res),
                      entry->rel, entry->page,
                      entry->offset, false);
    }
    else if (ISSIGNKEY(DatumGetPointer(entry->key)) &&
             !ISALLTRUE(DatumGetPointer(entry->key)))
    {
        int32       i,
                    len;
        SignTSVector *res;
        BITVECP     sign = GETSIGN(DatumGetPointer(entry->key));

        LOOPBYTE
        {
            if ((sign[i] & 0xff) != 0xff)
                PG_RETURN_POINTER(retval);
        }

        len = CALCGTSIZE(SIGNKEY | ALLISTRUE, 0);
        res = (SignTSVector *) palloc(len);
        SET_VARSIZE(res, len);
        res->flag = SIGNKEY | ALLISTRUE;

        retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));
        gistentryinit(*retval, PointerGetDatum(res),
                      entry->rel, entry->page,
                      entry->offset, false);
    }
    PG_RETURN_POINTER(retval);
}

Datum
gtsvector_decompress(PG_FUNCTION_ARGS)
{
    /*
     * We need to detoast the stored value, because the other gtsvector
     * support functions don't cope with toasted values.
     */
    GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
    SignTSVector *key = (SignTSVector *) PG_DETOAST_DATUM(entry->key);

    if (key != (SignTSVector *) DatumGetPointer(entry->key))
    {
        GISTENTRY  *retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));

        gistentryinit(*retval, PointerGetDatum(key),
                      entry->rel, entry->page,
                      entry->offset, false);

        PG_RETURN_POINTER(retval);
    }

    PG_RETURN_POINTER(entry);
}

typedef struct
{
    int32      *arrb;
    int32      *arre;
} CHKVAL;

/*
 * is there value 'val' in array or not ?
 */
static bool
checkcondition_arr(void *checkval, QueryOperand *val, ExecPhraseData *data)
{
    int32      *StopLow = ((CHKVAL *) checkval)->arrb;
    int32      *StopHigh = ((CHKVAL *) checkval)->arre;
    int32      *StopMiddle;

    /* Loop invariant: StopLow <= val < StopHigh */

    /*
     * we are not able to find a prefix by hash value
     */
    if (val->prefix)
        return true;

    while (StopLow < StopHigh)
    {
        StopMiddle = StopLow + (StopHigh - StopLow) / 2;
        if (*StopMiddle == val->valcrc)
            return true;
        else if (*StopMiddle < val->valcrc)
            StopLow = StopMiddle + 1;
        else
            StopHigh = StopMiddle;
    }

    return false;
}

static bool
checkcondition_bit(void *checkval, QueryOperand *val, ExecPhraseData *data)
{
    /*
     * we are not able to find a prefix in signature tree
     */
    if (val->prefix)
        return true;
    return GETBIT(checkval, HASHVAL(val->valcrc));
}

Datum
gtsvector_consistent(PG_FUNCTION_ARGS)
{
    GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
    TSQuery     query = PG_GETARG_TSQUERY(1);

    /* StrategyNumber strategy = (StrategyNumber) PG_GETARG_UINT16(2); */
    /* Oid      subtype = PG_GETARG_OID(3); */
    bool       *recheck = (bool *) PG_GETARG_POINTER(4);
    SignTSVector *key = (SignTSVector *) DatumGetPointer(entry->key);

    /* All cases served by this function are inexact */
    *recheck = true;

    if (!query->size)
        PG_RETURN_BOOL(false);

    if (ISSIGNKEY(key))
    {
        if (ISALLTRUE(key))
            PG_RETURN_BOOL(true);

        /* since signature is lossy, cannot specify CALC_NOT here */
        PG_RETURN_BOOL(TS_execute(GETQUERY(query),
                                  (void *) GETSIGN(key),
                                  TS_EXEC_PHRASE_NO_POS,
                                  checkcondition_bit));
    }
    else
    {                           /* only leaf pages */
        CHKVAL      chkval;

        chkval.arrb = GETARR(key);
        chkval.arre = chkval.arrb + ARRNELEM(key);
        PG_RETURN_BOOL(TS_execute(GETQUERY(query),
                                  (void *) &chkval,
                                  TS_EXEC_PHRASE_NO_POS | TS_EXEC_CALC_NOT,
                                  checkcondition_arr));
    }
}

static int32
unionkey(BITVECP sbase, SignTSVector *add)
{
    int32       i;

    if (ISSIGNKEY(add))
    {
        BITVECP     sadd = GETSIGN(add);

        if (ISALLTRUE(add))
            return 1;

        LOOPBYTE
            sbase[i] |= sadd[i];
    }
    else
    {
        int32      *ptr = GETARR(add);

        for (i = 0; i < ARRNELEM(add); i++)
            HASH(sbase, ptr[i]);
    }
    return 0;
}


Datum
gtsvector_union(PG_FUNCTION_ARGS)
{
    GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
    int        *size = (int *) PG_GETARG_POINTER(1);
    BITVEC      base;
    int32       i,
                len;
    int32       flag = 0;
    SignTSVector *result;

    MemSet((void *) base, 0, sizeof(BITVEC));
    for (i = 0; i < entryvec->n; i++)
    {
        if (unionkey(base, GETENTRY(entryvec, i)))
        {
            flag = ALLISTRUE;
            break;
        }
    }

    flag |= SIGNKEY;
    len = CALCGTSIZE(flag, 0);
    result = (SignTSVector *) palloc(len);
    *size = len;
    SET_VARSIZE(result, len);
    result->flag = flag;
    if (!ISALLTRUE(result))
        memcpy((void *) GETSIGN(result), (void *) base, sizeof(BITVEC));

    PG_RETURN_POINTER(result);
}

Datum
gtsvector_same(PG_FUNCTION_ARGS)
{
    SignTSVector *a = (SignTSVector *) PG_GETARG_POINTER(0);
    SignTSVector *b = (SignTSVector *) PG_GETARG_POINTER(1);
    bool       *result = (bool *) PG_GETARG_POINTER(2);

    if (ISSIGNKEY(a))
    {                           /* then b also ISSIGNKEY */
        if (ISALLTRUE(a) && ISALLTRUE(b))
            *result = true;
        else if (ISALLTRUE(a))
            *result = false;
        else if (ISALLTRUE(b))
            *result = false;
        else
        {
            int32       i;
            BITVECP     sa = GETSIGN(a),
                        sb = GETSIGN(b);

            *result = true;
            LOOPBYTE
            {
                if (sa[i] != sb[i])
                {
                    *result = false;
                    break;
                }
            }
        }
    }
    else
    {                           /* a and b ISARRKEY */
        int32       lena = ARRNELEM(a),
                    lenb = ARRNELEM(b);

        if (lena != lenb)
            *result = false;
        else
        {
            int32      *ptra = GETARR(a),
                       *ptrb = GETARR(b);
            int32       i;

            *result = true;
            for (i = 0; i < lena; i++)
                if (ptra[i] != ptrb[i])
                {
                    *result = false;
                    break;
                }
        }
    }

    PG_RETURN_POINTER(result);
}

static int32
sizebitvec(BITVECP sign)
{
    return pg_popcount(sign, SIGLEN);
}

static int
hemdistsign(BITVECP a, BITVECP b)
{
    int         i,
                diff,
                dist = 0;

    LOOPBYTE
    {
        diff = (unsigned char) (a[i] ^ b[i]);
        /* Using the popcount functions here isn't likely to win */
        dist += pg_number_of_ones[diff];
    }
    return dist;
}

static int
hemdist(SignTSVector *a, SignTSVector *b)
{
    if (ISALLTRUE(a))
    {
        if (ISALLTRUE(b))
            return 0;
        else
            return SIGLENBIT - sizebitvec(GETSIGN(b));
    }
    else if (ISALLTRUE(b))
        return SIGLENBIT - sizebitvec(GETSIGN(a));

    return hemdistsign(GETSIGN(a), GETSIGN(b));
}

Datum
gtsvector_penalty(PG_FUNCTION_ARGS)
{
    GISTENTRY  *origentry = (GISTENTRY *) PG_GETARG_POINTER(0); /* always ISSIGNKEY */
    GISTENTRY  *newentry = (GISTENTRY *) PG_GETARG_POINTER(1);
    float      *penalty = (float *) PG_GETARG_POINTER(2);
    SignTSVector *origval = (SignTSVector *) DatumGetPointer(origentry->key);
    SignTSVector *newval = (SignTSVector *) DatumGetPointer(newentry->key);
    BITVECP     orig = GETSIGN(origval);

    *penalty = 0.0;

    if (ISARRKEY(newval))
    {
        BITVEC      sign;

        makesign(sign, newval);

        if (ISALLTRUE(origval))
            *penalty = ((float) (SIGLENBIT - sizebitvec(sign))) / (float) (SIGLENBIT + 1);
        else
            *penalty = hemdistsign(sign, orig);
    }
    else
        *penalty = hemdist(origval, newval);
    PG_RETURN_POINTER(penalty);
}

typedef struct
{
    bool        allistrue;
    BITVEC      sign;
} CACHESIGN;

static void
fillcache(CACHESIGN *item, SignTSVector *key)
{
    item->allistrue = false;
    if (ISARRKEY(key))
        makesign(item->sign, key);
    else if (ISALLTRUE(key))
        item->allistrue = true;
    else
        memcpy((void *) item->sign, (void *) GETSIGN(key), sizeof(BITVEC));
}

#define WISH_F(a,b,c) (double)( -(double)(((a)-(b))*((a)-(b))*((a)-(b)))*(c) )
typedef struct
{
    OffsetNumber pos;
    int32       cost;
} SPLITCOST;

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

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


static int
hemdistcache(CACHESIGN *a, CACHESIGN *b)
{
    if (a->allistrue)
    {
        if (b->allistrue)
            return 0;
        else
            return SIGLENBIT - sizebitvec(b->sign);
    }
    else if (b->allistrue)
        return SIGLENBIT - sizebitvec(a->sign);

    return hemdistsign(a->sign, b->sign);
}

Datum
gtsvector_picksplit(PG_FUNCTION_ARGS)
{
    GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
    GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1);
    OffsetNumber k,
                j;
    SignTSVector *datum_l,
               *datum_r;
    BITVECP     union_l,
                union_r;
    int32       size_alpha,
                size_beta;
    int32       size_waste,
                waste = -1;
    int32       nbytes;
    OffsetNumber seed_1 = 0,
                seed_2 = 0;
    OffsetNumber *left,
               *right;
    OffsetNumber maxoff;
    BITVECP     ptr;
    int         i;
    CACHESIGN  *cache;
    SPLITCOST  *costvector;

    maxoff = entryvec->n - 2;
    nbytes = (maxoff + 2) * sizeof(OffsetNumber);
    v->spl_left = (OffsetNumber *) palloc(nbytes);
    v->spl_right = (OffsetNumber *) palloc(nbytes);

    cache = (CACHESIGN *) palloc(sizeof(CACHESIGN) * (maxoff + 2));
    fillcache(&cache[FirstOffsetNumber], GETENTRY(entryvec, FirstOffsetNumber));

    for (k = FirstOffsetNumber; k < maxoff; k = OffsetNumberNext(k))
    {
        for (j = OffsetNumberNext(k); j <= maxoff; j = OffsetNumberNext(j))
        {
            if (k == FirstOffsetNumber)
                fillcache(&cache[j], GETENTRY(entryvec, j));

            size_waste = hemdistcache(&(cache[j]), &(cache[k]));
            if (size_waste > waste)
            {
                waste = size_waste;
                seed_1 = k;
                seed_2 = j;
            }
        }
    }

    left = v->spl_left;
    v->spl_nleft = 0;
    right = v->spl_right;
    v->spl_nright = 0;

    if (seed_1 == 0 || seed_2 == 0)
    {
        seed_1 = 1;
        seed_2 = 2;
    }

    /* form initial .. */
    if (cache[seed_1].allistrue)
    {
        datum_l = (SignTSVector *) palloc(CALCGTSIZE(SIGNKEY | ALLISTRUE, 0));
        SET_VARSIZE(datum_l, CALCGTSIZE(SIGNKEY | ALLISTRUE, 0));
        datum_l->flag = SIGNKEY | ALLISTRUE;
    }
    else
    {
        datum_l = (SignTSVector *) palloc(CALCGTSIZE(SIGNKEY, 0));
        SET_VARSIZE(datum_l, CALCGTSIZE(SIGNKEY, 0));
        datum_l->flag = SIGNKEY;
        memcpy((void *) GETSIGN(datum_l), (void *) cache[seed_1].sign, sizeof(BITVEC));
    }
    if (cache[seed_2].allistrue)
    {
        datum_r = (SignTSVector *) palloc(CALCGTSIZE(SIGNKEY | ALLISTRUE, 0));
        SET_VARSIZE(datum_r, CALCGTSIZE(SIGNKEY | ALLISTRUE, 0));
        datum_r->flag = SIGNKEY | ALLISTRUE;
    }
    else
    {
        datum_r = (SignTSVector *) palloc(CALCGTSIZE(SIGNKEY, 0));
        SET_VARSIZE(datum_r, CALCGTSIZE(SIGNKEY, 0));
        datum_r->flag = SIGNKEY;
        memcpy((void *) GETSIGN(datum_r), (void *) cache[seed_2].sign, sizeof(BITVEC));
    }

    union_l = GETSIGN(datum_l);
    union_r = GETSIGN(datum_r);
    maxoff = OffsetNumberNext(maxoff);
    fillcache(&cache[maxoff], GETENTRY(entryvec, maxoff));
    /* sort before ... */
    costvector = (SPLITCOST *) palloc(sizeof(SPLITCOST) * maxoff);
    for (j = FirstOffsetNumber; j <= maxoff; j = OffsetNumberNext(j))
    {
        costvector[j - 1].pos = j;
        size_alpha = hemdistcache(&(cache[seed_1]), &(cache[j]));
        size_beta = hemdistcache(&(cache[seed_2]), &(cache[j]));
        costvector[j - 1].cost = Abs(size_alpha - size_beta);
    }
    qsort((void *) costvector, maxoff, sizeof(SPLITCOST), comparecost);

    for (k = 0; k < maxoff; k++)
    {
        j = costvector[k].pos;
        if (j == seed_1)
        {
            *left++ = j;
            v->spl_nleft++;
            continue;
        }
        else if (j == seed_2)
        {
            *right++ = j;
            v->spl_nright++;
            continue;
        }

        if (ISALLTRUE(datum_l) || cache[j].allistrue)
        {
            if (ISALLTRUE(datum_l) && cache[j].allistrue)
                size_alpha = 0;
            else
                size_alpha = SIGLENBIT - sizebitvec(
                                                    (cache[j].allistrue) ? GETSIGN(datum_l) : GETSIGN(cache[j].sign)
                    );
        }
        else
            size_alpha = hemdistsign(cache[j].sign, GETSIGN(datum_l));

        if (ISALLTRUE(datum_r) || cache[j].allistrue)
        {
            if (ISALLTRUE(datum_r) && cache[j].allistrue)
                size_beta = 0;
            else
                size_beta = SIGLENBIT - sizebitvec(
                                                   (cache[j].allistrue) ? GETSIGN(datum_r) : GETSIGN(cache[j].sign)
                    );
        }
        else
            size_beta = hemdistsign(cache[j].sign, GETSIGN(datum_r));

        if (size_alpha < size_beta + WISH_F(v->spl_nleft, v->spl_nright, 0.1))
        {
            if (ISALLTRUE(datum_l) || cache[j].allistrue)
            {
                if (!ISALLTRUE(datum_l))
                    MemSet((void *) GETSIGN(datum_l), 0xff, sizeof(BITVEC));
            }
            else
            {
                ptr = cache[j].sign;
                LOOPBYTE
                    union_l[i] |= ptr[i];
            }
            *left++ = j;
            v->spl_nleft++;
        }
        else
        {
            if (ISALLTRUE(datum_r) || cache[j].allistrue)
            {
                if (!ISALLTRUE(datum_r))
                    MemSet((void *) GETSIGN(datum_r), 0xff, sizeof(BITVEC));
            }
            else
            {
                ptr = cache[j].sign;
                LOOPBYTE
                    union_r[i] |= ptr[i];
            }
            *right++ = j;
            v->spl_nright++;
        }
    }

    *right = *left = FirstOffsetNumber;
    v->spl_ldatum = PointerGetDatum(datum_l);
    v->spl_rdatum = PointerGetDatum(datum_r);

    PG_RETURN_POINTER(v);
}

/*
 * Formerly, gtsvector_consistent was declared in pg_proc.h with arguments
 * that did not match the documented conventions for GiST support functions.
 * We fixed that, but we still need a pg_proc entry with the old signature
 * to support reloading pre-9.6 contrib/tsearch2 opclass declarations.
 * This compatibility function should go away eventually.
 */
Datum
gtsvector_consistent_oldsig(PG_FUNCTION_ARGS)
{
    return gtsvector_consistent(fcinfo);
}