greenplumn spgtextproc 源码
greenplumn spgtextproc 代码
文件路径：/src/backend/access/spgist/spgtextproc.c
/*-------------------------------------------------------------------------
*
* spgtextproc.c
* implementation of radix tree (compressed trie) over text
*
* In a text_ops SPGiST index, inner tuples can have a prefix which is the
* common prefix of all strings indexed under that tuple. The node labels
* represent the next byte of the string(s) after the prefix. Assuming we
* always use the longest possible prefix, we will get more than one node
* label unless the prefix length is restricted by SPGIST_MAX_PREFIX_LENGTH.
*
* To reconstruct the indexed string for any index entry, concatenate the
* inner-tuple prefixes and node labels starting at the root and working
* down to the leaf entry, then append the datum in the leaf entry.
* (While descending the tree, "level" is the number of bytes reconstructed
* so far.)
*
* However, there are two special cases for node labels: -1 indicates that
* there are no more bytes after the prefix-so-far, and -2 indicates that we
* had to split an existing allTheSame tuple (in such a case we have to create
* a node label that doesn't correspond to any string byte). In either case,
* the node label does not contribute anything to the reconstructed string.
*
* Previously, we used a node label of zero for both special cases, but
* this was problematic because one can't tell whether a string ending at
* the current level can be pushed down into such a child node. For
* backwards compatibility, we still support such node labels for reading;
* but no new entries will ever be pushed down into a zero-labeled child.
* No new entries ever get pushed into a -2-labeled child, either.
*
*
* Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/access/spgist/spgtextproc.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/spgist.h"
#include "catalog/pg_type.h"
#include "mb/pg_wchar.h"
#include "utils/builtins.h"
#include "utils/datum.h"
#include "utils/pg_locale.h"
#include "utils/varlena.h"
/*
* In the worst case, an inner tuple in a text radix tree could have as many
* as 258 nodes (one for each possible byte value, plus the two special
* cases). Each node can take 16 bytes on MAXALIGN=8 machines. The inner
* tuple must fit on an index page of size BLCKSZ. Rather than assuming we
* know the exact amount of overhead imposed by page headers, tuple headers,
* etc, we leave 100 bytes for that (the actual overhead should be no more
* than 56 bytes at this writing, so there is slop in this number).
* So we can safely create prefixes up to BLCKSZ - 258 * 16 - 100 bytes long.
* Unfortunately, because 258 * 16 is over 4K, there is no safe prefix length
* when BLCKSZ is less than 8K; it is always possible to get "SPGiST inner
* tuple size exceeds maximum" if there are too many distinct next-byte values
* at a given place in the tree. Since use of nonstandard block sizes appears
* to be negligible in the field, we just live with that fact for now,
* choosing a max prefix size of 32 bytes when BLCKSZ is configured smaller
* than default.
*/
#define SPGIST_MAX_PREFIX_LENGTH Max((int) (BLCKSZ - 258 * 16 - 100), 32)
/*
* Strategy for collation aware operator on text is equal to btree strategy
* plus value of 10.
*
* Current collation aware strategies and their corresponding btree strategies:
* 11 BTLessStrategyNumber
* 12 BTLessEqualStrategyNumber
* 14 BTGreaterEqualStrategyNumber
* 15 BTGreaterStrategyNumber
*/
#define SPG_STRATEGY_ADDITION (10)
#define SPG_IS_COLLATION_AWARE_STRATEGY(s) ((s) > SPG_STRATEGY_ADDITION \
&& (s) != RTPrefixStrategyNumber)
/* Struct for sorting values in picksplit */
typedef struct spgNodePtr
{
Datum d;
int i;
int16 c;
} spgNodePtr;
Datum
spg_text_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->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;
}
Datum
spg_text_choose(PG_FUNCTION_ARGS)
{
spgChooseIn *in = (spgChooseIn *) PG_GETARG_POINTER(0);
spgChooseOut *out = (spgChooseOut *) PG_GETARG_POINTER(1);
text *inText = DatumGetTextPP(in->datum);
char *inStr = VARDATA_ANY(inText);
int inSize = VARSIZE_ANY_EXHDR(inText);
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();
}
/* qsort comparator to sort spgNodePtr structs by "c" */
static int
cmpNodePtr(const void *a, const void *b)
{
const spgNodePtr *aa = (const spgNodePtr *) a;
const spgNodePtr *bb = (const spgNodePtr *) b;
return aa->c - bb->c;
}
Datum
spg_text_picksplit(PG_FUNCTION_ARGS)
{
spgPickSplitIn *in = (spgPickSplitIn *) PG_GETARG_POINTER(0);
spgPickSplitOut *out = (spgPickSplitOut *) PG_GETARG_POINTER(1);
text *text0 = DatumGetTextPP(in->datums[0]);
int i,
commonLen;
spgNodePtr *nodes;
/* Identify longest common prefix, if any */
commonLen = VARSIZE_ANY_EXHDR(text0);
for (i = 1; i < in->nTuples && commonLen > 0; i++)
{
text *texti = DatumGetTextPP(in->datums[i]);
int tmp = commonPrefix(VARDATA_ANY(text0),
VARDATA_ANY(texti),
VARSIZE_ANY_EXHDR(text0),
VARSIZE_ANY_EXHDR(texti));
if (tmp < commonLen)
commonLen = tmp;
}
/*
* Limit the prefix length, if necessary, to ensure that the resulting
* inner tuple will fit on a page.
*/
commonLen = Min(commonLen, SPGIST_MAX_PREFIX_LENGTH);
/* Set node prefix to be that string, if it's not empty */
if (commonLen == 0)
{
out->hasPrefix = false;
}
else
{
out->hasPrefix = true;
out->prefixDatum = formTextDatum(VARDATA_ANY(text0), commonLen);
}
/* Extract the node label (first non-common byte) from each value */
nodes = (spgNodePtr *) palloc(sizeof(spgNodePtr) * in->nTuples);
for (i = 0; i < in->nTuples; i++)
{
text *texti = DatumGetTextPP(in->datums[i]);
if (commonLen < VARSIZE_ANY_EXHDR(texti))
nodes[i].c = *(unsigned char *) (VARDATA_ANY(texti) + commonLen);
else
nodes[i].c = -1; /* use -1 if string is all common */
nodes[i].i = i;
nodes[i].d = in->datums[i];
}
/*
* Sort by label values so that we can group the values into nodes. This
* also ensures that the nodes are ordered by label value, allowing the
* use of binary search in searchChar.
*/
qsort(nodes, in->nTuples, sizeof(*nodes), cmpNodePtr);
/* And emit results */
out->nNodes = 0;
out->nodeLabels = (Datum *) palloc(sizeof(Datum) * in->nTuples);
out->mapTuplesToNodes = (int *) palloc(sizeof(int) * in->nTuples);
out->leafTupleDatums = (Datum *) palloc(sizeof(Datum) * in->nTuples);
for (i = 0; i < in->nTuples; i++)
{
text *texti = DatumGetTextPP(nodes[i].d);
Datum leafD;
if (i == 0 || nodes[i].c != nodes[i - 1].c)
{
out->nodeLabels[out->nNodes] = Int16GetDatum(nodes[i].c);
out->nNodes++;
}
if (commonLen < VARSIZE_ANY_EXHDR(texti))
leafD = formTextDatum(VARDATA_ANY(texti) + commonLen + 1,
VARSIZE_ANY_EXHDR(texti) - commonLen - 1);
else
leafD = formTextDatum(NULL, 0);
out->leafTupleDatums[nodes[i].i] = leafD;
out->mapTuplesToNodes[nodes[i].i] = out->nNodes - 1;
}
PG_RETURN_VOID();
}
Datum
spg_text_inner_consistent(PG_FUNCTION_ARGS)
{
spgInnerConsistentIn *in = (spgInnerConsistentIn *) PG_GETARG_POINTER(0);
spgInnerConsistentOut *out = (spgInnerConsistentOut *) PG_GETARG_POINTER(1);
bool collate_is_c = lc_collate_is_c(PG_GET_COLLATION());
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.
*
* 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;
text *inText;
int inSize;
int r;
/*
* If it's a collation-aware operator, but the collation is C, we
* can treat it as non-collation-aware. With non-C collation we
* need to traverse whole tree :-( so there's no point in making
* any check here. (Note also that our reconstructed value may
* well end with a partial multibyte character, so that applying
* any encoding-sensitive test to it would be risky anyhow.)
*/
if (SPG_IS_COLLATION_AWARE_STRATEGY(strategy))
{
if (collate_is_c)
strategy -= SPG_STRATEGY_ADDITION;
else
continue;
}
inText = DatumGetTextPP(in->scankeys[j].sk_argument);
inSize = VARSIZE_ANY_EXHDR(inText);
r = memcmp(VARDATA(reconstrText), VARDATA_ANY(inText),
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;
case RTPrefixStrategyNumber:
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();
}
Datum
spg_text_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 full string represented by this leaf tuple */
fullLen = level + VARSIZE_ANY_EXHDR(leafValue);
if (VARSIZE_ANY_EXHDR(leafValue) == 0 && level > 0)
{
fullValue = VARDATA(reconstrValue);
out->leafValue = PointerGetDatum(reconstrValue);
}
else
{
text *fullText = palloc(VARHDRSZ + fullLen);
SET_VARSIZE(fullText, VARHDRSZ + fullLen);
fullValue = VARDATA(fullText);
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(fullText);
}
/* Perform the required comparison(s) */
res = true;
for (j = 0; j < in->nkeys; j++)
{
StrategyNumber strategy = in->scankeys[j].sk_strategy;
text *query = DatumGetTextPP(in->scankeys[j].sk_argument);
int queryLen = VARSIZE_ANY_EXHDR(query);
int r;
if (strategy == RTPrefixStrategyNumber)
{
/*
* if level >= length of query then reconstrValue must begin with
* query (prefix) string, so we don't need to check it again.
*/
res = (level >= queryLen) ||
DatumGetBool(DirectFunctionCall2Coll(text_starts_with,
PG_GET_COLLATION(),
out->leafValue,
PointerGetDatum(query)));
if (!res) /* no need to consider remaining conditions */
break;
continue;
}
if (SPG_IS_COLLATION_AWARE_STRATEGY(strategy))
{
/* Collation-aware comparison */
strategy -= SPG_STRATEGY_ADDITION;
/* If asserts enabled, verify encoding of reconstructed string */
Assert(pg_verifymbstr(fullValue, fullLen, false));
r = varstr_cmp(fullValue, fullLen,
VARDATA_ANY(query), queryLen,
PG_GET_COLLATION());
}
else
{
/* Non-collation-aware comparison */
r = memcmp(fullValue, VARDATA_ANY(query), 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);
}
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