spgist_name_ops.c

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/*--------------------------------------------------------------------------
 *
 * spgist_name_ops.c
 *      Test opclass for SP-GiST
 *
 * This indexes input values of type "name", but the index storage is "text",
 * with the same choices as made in the core SP-GiST text_ops opclass.
 * Much of the code is identical to src/backend/access/spgist/spgtextproc.c,
 * which see for a more detailed header comment.
 *
 * Unlike spgtextproc.c, we don't bother with collation-aware logic.
 *
 *
 * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *      src/test/modules/spgist_name_ops/spgist_name_ops.c
 *
 * -------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "access/spgist.h"
#include "catalog/pg_type.h"
#include "utils/datum.h"
#include "varatt.h"
 
PG_MODULE_MAGIC;
 
 
PG_FUNCTION_INFO_V1(spgist_name_config);
Datum
spgist_name_config(PG_FUNCTION_ARGS)
{
    /* spgConfigIn *cfgin = (spgConfigIn *) PG_GETARG_POINTER(0); */
    spgConfigOut *cfg = (spgConfigOut *) PG_GETARG_POINTER(1);
 
    cfg->prefixType = TEXTOID;
    cfg->labelType = INT2OID;
    cfg->leafType = TEXTOID;
    cfg->canReturnData = true;
    cfg->longValuesOK = true;   /* suffixing will shorten long values */
    PG_RETURN_VOID();
}
 
/*
 * Form a text datum from the given not-necessarily-null-terminated string,
 * using short varlena header format if possible
 */
static Datum
formTextDatum(const char *data, int datalen)
{
    char       *p;
 
    p = (char *) palloc(datalen + VARHDRSZ);
 
    if (datalen + VARHDRSZ_SHORT <= VARATT_SHORT_MAX)
    {
        SET_VARSIZE_SHORT(p, datalen + VARHDRSZ_SHORT);
        if (datalen)
            memcpy(p + VARHDRSZ_SHORT, data, datalen);
    }
    else
    {
        SET_VARSIZE(p, datalen + VARHDRSZ);
        memcpy(p + VARHDRSZ, data, datalen);
    }
 
    return PointerGetDatum(p);
}
 
/*
 * Find the length of the common prefix of a and b
 */
static int
commonPrefix(const char *a, const char *b, int lena, int lenb)
{
    int         i = 0;
 
    while (i < lena && i < lenb && *a == *b)
    {
        a++;
        b++;
        i++;
    }
 
    return i;
}
 
/*
 * Binary search an array of int16 datums for a match to c
 *
 * On success, *i gets the match location; on failure, it gets where to insert
 */
static bool
searchChar(Datum *nodeLabels, int nNodes, int16 c, int *i)
{
    int         StopLow = 0,
                StopHigh = nNodes;
 
    while (StopLow < StopHigh)
    {
        int         StopMiddle = (StopLow + StopHigh) >> 1;
        int16       middle = DatumGetInt16(nodeLabels[StopMiddle]);
 
        if (c < middle)
            StopHigh = StopMiddle;
        else if (c > middle)
            StopLow = StopMiddle + 1;
        else
        {
            *i = StopMiddle;
            return true;
        }
    }
 
    *i = StopHigh;
    return false;
}
 
PG_FUNCTION_INFO_V1(spgist_name_choose);
Datum
spgist_name_choose(PG_FUNCTION_ARGS)
{
    spgChooseIn *in = (spgChooseIn *) PG_GETARG_POINTER(0);
    spgChooseOut *out = (spgChooseOut *) PG_GETARG_POINTER(1);
    Name        inName = DatumGetName(in->datum);
    char       *inStr = NameStr(*inName);
    int         inSize = strlen(inStr);
    char       *prefixStr = NULL;
    int         prefixSize = 0;
    int         commonLen = 0;
    int16       nodeChar = 0;
    int         i = 0;
 
    /* Check for prefix match, set nodeChar to first byte after prefix */
    if (in->hasPrefix)
    {
        text       *prefixText = DatumGetTextPP(in->prefixDatum);
 
        prefixStr = VARDATA_ANY(prefixText);
        prefixSize = VARSIZE_ANY_EXHDR(prefixText);
 
        commonLen = commonPrefix(inStr + in->level,
                                 prefixStr,
                                 inSize - in->level,
                                 prefixSize);
 
        if (commonLen == prefixSize)
        {
            if (inSize - in->level > commonLen)
                nodeChar = *(unsigned char *) (inStr + in->level + commonLen);
            else
                nodeChar = -1;
        }
        else
        {
            /* Must split tuple because incoming value doesn't match prefix */
            out->resultType = spgSplitTuple;
 
            if (commonLen == 0)
            {
                out->result.splitTuple.prefixHasPrefix = false;
            }
            else
            {
                out->result.splitTuple.prefixHasPrefix = true;
                out->result.splitTuple.prefixPrefixDatum =
                    formTextDatum(prefixStr, commonLen);
            }
            out->result.splitTuple.prefixNNodes = 1;
            out->result.splitTuple.prefixNodeLabels =
                (Datum *) palloc(sizeof(Datum));
            out->result.splitTuple.prefixNodeLabels[0] =
                Int16GetDatum(*(unsigned char *) (prefixStr + commonLen));
 
            out->result.splitTuple.childNodeN = 0;
 
            if (prefixSize - commonLen == 1)
            {
                out->result.splitTuple.postfixHasPrefix = false;
            }
            else
            {
                out->result.splitTuple.postfixHasPrefix = true;
                out->result.splitTuple.postfixPrefixDatum =
                    formTextDatum(prefixStr + commonLen + 1,
                                  prefixSize - commonLen - 1);
            }
 
            PG_RETURN_VOID();
        }
    }
    else if (inSize > in->level)
    {
        nodeChar = *(unsigned char *) (inStr + in->level);
    }
    else
    {
        nodeChar = -1;
    }
 
    /* Look up nodeChar in the node label array */
    if (searchChar(in->nodeLabels, in->nNodes, nodeChar, &i))
    {
        /*
         * Descend to existing node.  (If in->allTheSame, the core code will
         * ignore our nodeN specification here, but that's OK.  We still have
         * to provide the correct levelAdd and restDatum values, and those are
         * the same regardless of which node gets chosen by core.)
         */
        int         levelAdd;
 
        out->resultType = spgMatchNode;
        out->result.matchNode.nodeN = i;
        levelAdd = commonLen;
        if (nodeChar >= 0)
            levelAdd++;
        out->result.matchNode.levelAdd = levelAdd;
        if (inSize - in->level - levelAdd > 0)
            out->result.matchNode.restDatum =
                formTextDatum(inStr + in->level + levelAdd,
                              inSize - in->level - levelAdd);
        else
            out->result.matchNode.restDatum =
                formTextDatum(NULL, 0);
    }
    else if (in->allTheSame)
    {
        /*
         * Can't use AddNode action, so split the tuple.  The upper tuple has
         * the same prefix as before and uses a dummy node label -2 for the
         * lower tuple.  The lower tuple has no prefix and the same node
         * labels as the original tuple.
         *
         * Note: it might seem tempting to shorten the upper tuple's prefix,
         * if it has one, then use its last byte as label for the lower tuple.
         * But that doesn't win since we know the incoming value matches the
         * whole prefix: we'd just end up splitting the lower tuple again.
         */
        out->resultType = spgSplitTuple;
        out->result.splitTuple.prefixHasPrefix = in->hasPrefix;
        out->result.splitTuple.prefixPrefixDatum = in->prefixDatum;
        out->result.splitTuple.prefixNNodes = 1;
        out->result.splitTuple.prefixNodeLabels = (Datum *) palloc(sizeof(Datum));
        out->result.splitTuple.prefixNodeLabels[0] = Int16GetDatum(-2);
        out->result.splitTuple.childNodeN = 0;
        out->result.splitTuple.postfixHasPrefix = false;
    }
    else
    {
        /* Add a node for the not-previously-seen nodeChar value */
        out->resultType = spgAddNode;
        out->result.addNode.nodeLabel = Int16GetDatum(nodeChar);
        out->result.addNode.nodeN = i;
    }
 
    PG_RETURN_VOID();
}
 
/* The picksplit function is identical to the core opclass, so just use that */
 
PG_FUNCTION_INFO_V1(spgist_name_inner_consistent);
Datum
spgist_name_inner_consistent(PG_FUNCTION_ARGS)
{
    spgInnerConsistentIn *in = (spgInnerConsistentIn *) PG_GETARG_POINTER(0);
    spgInnerConsistentOut *out = (spgInnerConsistentOut *) PG_GETARG_POINTER(1);
    text       *reconstructedValue;
    text       *reconstrText;
    int         maxReconstrLen;
    text       *prefixText = NULL;
    int         prefixSize = 0;
    int         i;
 
    /*
     * Reconstruct values represented at this tuple, including parent data,
     * prefix of this tuple if any, and the node label if it's non-dummy.
     * in->level should be the length of the previously reconstructed value,
     * and the number of bytes added here is prefixSize or prefixSize + 1.
     *
     * Recall that reconstructedValues are assumed to be the same type as leaf
     * datums, so we must use "text" not "name" for them.
     *
     * Note: we assume that in->reconstructedValue isn't toasted and doesn't
     * have a short varlena header.  This is okay because it must have been
     * created by a previous invocation of this routine, and we always emit
     * long-format reconstructed values.
     */
    reconstructedValue = (text *) DatumGetPointer(in->reconstructedValue);
    Assert(reconstructedValue == NULL ? in->level == 0 :
           VARSIZE_ANY_EXHDR(reconstructedValue) == in->level);
 
    maxReconstrLen = in->level + 1;
    if (in->hasPrefix)
    {
        prefixText = DatumGetTextPP(in->prefixDatum);
        prefixSize = VARSIZE_ANY_EXHDR(prefixText);
        maxReconstrLen += prefixSize;
    }
 
    reconstrText = palloc(VARHDRSZ + maxReconstrLen);
    SET_VARSIZE(reconstrText, VARHDRSZ + maxReconstrLen);
 
    if (in->level)
        memcpy(VARDATA(reconstrText),
               VARDATA(reconstructedValue),
               in->level);
    if (prefixSize)
        memcpy(((char *) VARDATA(reconstrText)) + in->level,
               VARDATA_ANY(prefixText),
               prefixSize);
    /* last byte of reconstrText will be filled in below */
 
    /*
     * Scan the child nodes.  For each one, complete the reconstructed value
     * and see if it's consistent with the query.  If so, emit an entry into
     * the output arrays.
     */
    out->nodeNumbers = (int *) palloc(sizeof(int) * in->nNodes);
    out->levelAdds = (int *) palloc(sizeof(int) * in->nNodes);
    out->reconstructedValues = (Datum *) palloc(sizeof(Datum) * in->nNodes);
    out->nNodes = 0;
 
    for (i = 0; i < in->nNodes; i++)
    {
        int16       nodeChar = DatumGetInt16(in->nodeLabels[i]);
        int         thisLen;
        bool        res = true;
        int         j;
 
        /* If nodeChar is a dummy value, don't include it in data */
        if (nodeChar <= 0)
            thisLen = maxReconstrLen - 1;
        else
        {
            ((unsigned char *) VARDATA(reconstrText))[maxReconstrLen - 1] = nodeChar;
            thisLen = maxReconstrLen;
        }
 
        for (j = 0; j < in->nkeys; j++)
        {
            StrategyNumber strategy = in->scankeys[j].sk_strategy;
            Name        inName;
            char       *inStr;
            int         inSize;
            int         r;
 
            inName = DatumGetName(in->scankeys[j].sk_argument);
            inStr = NameStr(*inName);
            inSize = strlen(inStr);
 
            r = memcmp(VARDATA(reconstrText), inStr,
                       Min(inSize, thisLen));
 
            switch (strategy)
            {
                case BTLessStrategyNumber:
                case BTLessEqualStrategyNumber:
                    if (r > 0)
                        res = false;
                    break;
                case BTEqualStrategyNumber:
                    if (r != 0 || inSize < thisLen)
                        res = false;
                    break;
                case BTGreaterEqualStrategyNumber:
                case BTGreaterStrategyNumber:
                    if (r < 0)
                        res = false;
                    break;
                default:
                    elog(ERROR, "unrecognized strategy number: %d",
                         in->scankeys[j].sk_strategy);
                    break;
            }
 
            if (!res)
                break;          /* no need to consider remaining conditions */
        }
 
        if (res)
        {
            out->nodeNumbers[out->nNodes] = i;
            out->levelAdds[out->nNodes] = thisLen - in->level;
            SET_VARSIZE(reconstrText, VARHDRSZ + thisLen);
            out->reconstructedValues[out->nNodes] =
                datumCopy(PointerGetDatum(reconstrText), false, -1);
            out->nNodes++;
        }
    }
 
    PG_RETURN_VOID();
}
 
PG_FUNCTION_INFO_V1(spgist_name_leaf_consistent);
Datum
spgist_name_leaf_consistent(PG_FUNCTION_ARGS)
{
    spgLeafConsistentIn *in = (spgLeafConsistentIn *) PG_GETARG_POINTER(0);
    spgLeafConsistentOut *out = (spgLeafConsistentOut *) PG_GETARG_POINTER(1);
    int         level = in->level;
    text       *leafValue,
               *reconstrValue = NULL;
    char       *fullValue;
    int         fullLen;
    bool        res;
    int         j;
 
    /* all tests are exact */
    out->recheck = false;
 
    leafValue = DatumGetTextPP(in->leafDatum);
 
    /* As above, in->reconstructedValue isn't toasted or short. */
    if (DatumGetPointer(in->reconstructedValue))
        reconstrValue = (text *) DatumGetPointer(in->reconstructedValue);
 
    Assert(reconstrValue == NULL ? level == 0 :
           VARSIZE_ANY_EXHDR(reconstrValue) == level);
 
    /* Reconstruct the Name represented by this leaf tuple */
    fullValue = palloc0(NAMEDATALEN);
    fullLen = level + VARSIZE_ANY_EXHDR(leafValue);
    Assert(fullLen < NAMEDATALEN);
    if (VARSIZE_ANY_EXHDR(leafValue) == 0 && level > 0)
    {
        memcpy(fullValue, VARDATA(reconstrValue),
               VARSIZE_ANY_EXHDR(reconstrValue));
    }
    else
    {
        if (level)
            memcpy(fullValue, VARDATA(reconstrValue), level);
        if (VARSIZE_ANY_EXHDR(leafValue) > 0)
            memcpy(fullValue + level, VARDATA_ANY(leafValue),
                   VARSIZE_ANY_EXHDR(leafValue));
    }
    out->leafValue = PointerGetDatum(fullValue);
 
    /* Perform the required comparison(s) */
    res = true;
    for (j = 0; j < in->nkeys; j++)
    {
        StrategyNumber strategy = in->scankeys[j].sk_strategy;
        Name        queryName = DatumGetName(in->scankeys[j].sk_argument);
        char       *queryStr = NameStr(*queryName);
        int         queryLen = strlen(queryStr);
        int         r;
 
        /* Non-collation-aware comparison */
        r = memcmp(fullValue, queryStr, Min(queryLen, fullLen));
 
        if (r == 0)
        {
            if (queryLen > fullLen)
                r = -1;
            else if (queryLen < fullLen)
                r = 1;
        }
 
        switch (strategy)
        {
            case BTLessStrategyNumber:
                res = (r < 0);
                break;
            case BTLessEqualStrategyNumber:
                res = (r <= 0);
                break;
            case BTEqualStrategyNumber:
                res = (r == 0);
                break;
            case BTGreaterEqualStrategyNumber:
                res = (r >= 0);
                break;
            case BTGreaterStrategyNumber:
                res = (r > 0);
                break;
            default:
                elog(ERROR, "unrecognized strategy number: %d",
                     in->scankeys[j].sk_strategy);
                res = false;
                break;
        }
 
        if (!res)
            break;              /* no need to consider remaining conditions */
    }
 
    PG_RETURN_BOOL(res);
}
 
PG_FUNCTION_INFO_V1(spgist_name_compress);
Datum
spgist_name_compress(PG_FUNCTION_ARGS)
{
    Name        inName = PG_GETARG_NAME(0);
    char       *inStr = NameStr(*inName);
 
    PG_RETURN_DATUM(formTextDatum(inStr, strlen(inStr)));
}