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Improve the performance of the ANALYZE command by taking advantage of the

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fact that every row of a UNIQUE index is distinct.

FossilOrigin-Name: 3e1e79e1335f7ad33cd35f384f2a063c4aa2253b
This commit is contained in:
drh
2014-07-23 18:36:55 +00:00
parent 11d451eb8a
commit 553818a0aa
3 changed files with 79 additions and 59 deletions
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124
src/analyze.c
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@@ -371,15 +371,20 @@ static void stat4Destructor(void *pOld){
/*
** Implementation of the stat_init(N,K,C) SQL function. The three parameters
** are:
** N: The number of columns in the index including the rowid/pk
** K: The number of columns in the index excluding the rowid/pk
** C: The number of rows in the index
** N: The number of columns in the index including the rowid/pk (note 1)
** K: The number of columns in the index excluding the rowid/pk.
** C: The number of rows in the index (note 2)
**
** C is only used for STAT3 and STAT4.
** Note 1: In the special case of the covering index that implements a
** WITHOUT ROWID table, N is the number of PRIMARY KEY columns, not the
** total number of columns in the table.
**
** For ordinary rowid tables, N==K+1. But for WITHOUT ROWID tables,
** N=K+P where P is the number of columns in the primary key. For the
** covering index that implements the original WITHOUT ROWID table, N==K.
** Note 2: C is only used for STAT3 and STAT4.
**
** For indexes on ordinary rowid tables, N==K+1. But for indexes on
** WITHOUT ROWID tables, N=K+P where P is the number of columns in the
** PRIMARY KEY of the table. The covering index that implements the
** original WITHOUT ROWID table as N==K as a special case.
**
** This routine allocates the Stat4Accum object in heap memory. The return
** value is a pointer to the the Stat4Accum object encoded as a blob (i.e.
@@ -689,7 +694,10 @@ static void samplePushPrevious(Stat4Accum *p, int iChng){
** R Rowid for the current row. Might be a key record for
** WITHOUT ROWID tables.
**
** The SQL function always returns NULL.
** This SQL function always returns NULL. It's purpose it to accumulate
** statistical data and/or samples in the Stat4Accum object about the
** index being analyzed. The stat_get() SQL function will later be used to
** extract relevant information for constructing the sqlite_statN tables.
**
** The R parameter is only used for STAT3 and STAT4
*/
@@ -783,7 +791,10 @@ static const FuncDef statPushFuncdef = {
/*
** Implementation of the stat_get(P,J) SQL function. This routine is
** used to query the results. Content is returned for parameter J
** used to query statistical information that has been gathered into
** the Stat4Accum object by prior calls to stat_push(). The P parameter
** is a BLOB which is decoded into a pointer to the Stat4Accum objects.
** The content to returned is determined by the parameter J
** which is one of the STAT_GET_xxxx values defined above.
**
** If neither STAT3 nor STAT4 are enabled, then J is always
@@ -1002,23 +1013,25 @@ static void analyzeOneTable(
sqlite3VdbeAddOp4(v, OP_String8, 0, regTabname, 0, pTab->zName, 0);
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
int nCol; /* Number of columns indexed by pIdx */
int nCol; /* Number of columns in pIdx. "N" */
int *aGotoChng; /* Array of jump instruction addresses */
int addrRewind; /* Address of "OP_Rewind iIdxCur" */
int addrGotoChng0; /* Address of "Goto addr_chng_0" */
int addrNextRow; /* Address of "next_row:" */
const char *zIdxName; /* Name of the index */
int nColTest; /* Number of columns to test for changes */
if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
if( pIdx->pPartIdxWhere==0 ) needTableCnt = 0;
if( !HasRowid(pTab) && IsPrimaryKeyIndex(pIdx) ){
nCol = pIdx->nKeyCol;
zIdxName = pTab->zName;
nColTest = nCol - 1;
}else{
nCol = pIdx->nColumn;
zIdxName = pIdx->zName;
nColTest = pIdx->onError==OE_None ? nCol-1 : pIdx->nKeyCol-1;
}
aGotoChng = sqlite3DbMallocRaw(db, sizeof(int)*(nCol+1));
aGotoChng = sqlite3DbMallocRaw(db, sizeof(int)*(nColTest+1));
if( aGotoChng==0 ) continue;
/* Populate the register containing the index name. */
@@ -1061,7 +1074,7 @@ static void analyzeOneTable(
** the regPrev array and a trailing rowid (the rowid slot is required
** when building a record to insert into the sample column of
** the sqlite_stat4 table. */
pParse->nMem = MAX(pParse->nMem, regPrev+nCol);
pParse->nMem = MAX(pParse->nMem, regPrev+nColTest);
/* Open a read-only cursor on the index being analyzed. */
assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) );
@@ -1071,10 +1084,13 @@ static void analyzeOneTable(
/* Invoke the stat_init() function. The arguments are:
**
** (1) the number of columns in the index including the rowid,
** (2) the number of rows in the index,
** (1) the number of columns in the index including the rowid
** (or for a WITHOUT ROWID table, the number of PK columns),
** (2) the number of columns in the key without the rowid/pk
** (3) the number of rows in the index,
**
** The second argument is only used for STAT3 and STAT4
**
** The third argument is only used for STAT3 and STAT4
*/
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regStat4+3);
@@ -1096,44 +1112,49 @@ static void analyzeOneTable(
addrRewind = sqlite3VdbeAddOp1(v, OP_Rewind, iIdxCur);
VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Integer, 0, regChng);
addrGotoChng0 = sqlite3VdbeAddOp0(v, OP_Goto);
/*
** next_row:
** regChng = 0
** if( idx(0) != regPrev(0) ) goto chng_addr_0
** regChng = 1
** if( idx(1) != regPrev(1) ) goto chng_addr_1
** ...
** regChng = N
** goto chng_addr_N
*/
addrNextRow = sqlite3VdbeCurrentAddr(v);
for(i=0; i<nCol-1; i++){
char *pColl = (char*)sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
sqlite3VdbeAddOp2(v, OP_Integer, i, regChng);
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regTemp);
aGotoChng[i] =
sqlite3VdbeAddOp4(v, OP_Ne, regTemp, 0, regPrev+i, pColl, P4_COLLSEQ);
sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
VdbeCoverage(v);
}
sqlite3VdbeAddOp2(v, OP_Integer, nCol-1, regChng);
aGotoChng[nCol] = sqlite3VdbeAddOp0(v, OP_Goto);
/*
** chng_addr_0:
** regPrev(0) = idx(0)
** chng_addr_1:
** regPrev(1) = idx(1)
** ...
*/
sqlite3VdbeJumpHere(v, addrGotoChng0);
for(i=0; i<nCol-1; i++){
sqlite3VdbeJumpHere(v, aGotoChng[i]);
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regPrev+i);
if( nColTest>0 ){
/*
** next_row:
** regChng = 0
** if( idx(0) != regPrev(0) ) goto chng_addr_0
** regChng = 1
** if( idx(1) != regPrev(1) ) goto chng_addr_1
** ...
** regChng = N
** goto chng_addr_N
*/
sqlite3VdbeAddOp0(v, OP_Goto);
addrNextRow = sqlite3VdbeCurrentAddr(v);
for(i=0; i<nColTest; i++){
char *pColl = (char*)sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
sqlite3VdbeAddOp2(v, OP_Integer, i, regChng);
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regTemp);
aGotoChng[i] =
sqlite3VdbeAddOp4(v, OP_Ne, regTemp, 0, regPrev+i, pColl, P4_COLLSEQ);
sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
VdbeCoverage(v);
}
sqlite3VdbeAddOp2(v, OP_Integer, nColTest, regChng);
aGotoChng[nColTest] = sqlite3VdbeAddOp0(v, OP_Goto);
/*
** chng_addr_0:
** regPrev(0) = idx(0)
** chng_addr_1:
** regPrev(1) = idx(1)
** ...
*/
sqlite3VdbeJumpHere(v, addrNextRow-1);
for(i=0; i<nColTest; i++){
sqlite3VdbeJumpHere(v, aGotoChng[i]);
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regPrev+i);
}
sqlite3VdbeJumpHere(v, aGotoChng[nColTest]);
}
/*
** chng_addr_N:
** regRowid = idx(rowid) // STAT34 only
@@ -1141,7 +1162,6 @@ static void analyzeOneTable(
** Next csr
** if !eof(csr) goto next_row;
*/
sqlite3VdbeJumpHere(v, aGotoChng[nCol]);
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
assert( regRowid==(regStat4+2) );
if( HasRowid(pTab) ){