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Begin a branch that experimentally replaces sqlite_stat2 with a new table

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called sqlite_stat3 that will hopefully facilitate better query
planning decisions.

FossilOrigin-Name: 52e1d7e8ddd4bb5ef3a9d00fd2d719a8a784f807
This commit is contained in:
drh
2011-08-12 01:51:45 +00:00
parent 90315a2417
commit faacf17cc1
13 changed files with 714 additions and 455 deletions
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501
src/analyze.c
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@@ -10,6 +10,95 @@
**
*************************************************************************
** This file contains code associated with the ANALYZE command.
**
** The ANALYZE command gather statistics about the content of tables
** and indices. These statistics are made available to the query planner
** to help it make better decisions about how to perform queries.
**
** The following system tables are or have been supported:
**
** CREATE TABLE sqlite_stat1(tbl, idx, stat);
** CREATE TABLE sqlite_stat2(tbl, idx, sampleno, sample);
** CREATE TABLE sqlite_stat3(tbl, idx, nLt, nEq, sample);
**
** Additional tables might be added in future releases of SQLite.
** The sqlite_stat2 table is not created or used unless the SQLite version
** is between 3.6.18 and 3.7.7, inclusive, and unless SQLite is compiled
** with SQLITE_ENABLE_STAT2. The sqlite_stat2 table is deprecated.
** The sqlite_stat2 table is superceded by sqlite_stat3, which is only
** created and used by SQLite versions after 2011-08-09 with
** SQLITE_ENABLE_STAT3 defined. The fucntionality of sqlite_stat3
** is a superset of sqlite_stat2.
**
** Format of sqlite_stat1:
**
** There is normally one row per index, with the index identified by the
** name in the idx column. The tbl column is the name of the table to
** which the index belongs. In each such row, the stat column will be
** a string consisting of a list of integers. The first integer in this
** list is the number of rows in the index and in the table. The second
** integer is the average number of rows in the index that have the same
** value in the first column of the index. The third integer is the average
** number of rows in the index that have the same value for the first two
** columns. The N-th integer (for N>1) is the average number of rows in
** the index which have the same value for the first N-1 columns. For
** a K-column index, there will be K+1 integers in the stat column. If
** the index is unique, then the last integer will be 1.
**
** The list of integers in the stat column can optionally be followed
** by the keyword "unordered". The "unordered" keyword, if it is present,
** must be separated from the last integer by a single space. If the
** "unordered" keyword is present, then the query planner assumes that
** the index is unordered and will not use the index for a range query.
**
** If the sqlite_stat1.idx column is NULL, then the sqlite_stat1.stat
** column contains a single integer which is the (estimated) number of
** rows in the table identified by sqlite_stat1.tbl.
**
** Format of sqlite_stat2:
**
** The sqlite_stat2 is only created and is only used if SQLite is compiled
** with SQLITE_ENABLE_STAT2 and if the SQLite version number is between
** 3.6.18 and 3.7.7. The "stat2" table contains additional information
** about the distribution of keys within an index. The index is identified by
** the "idx" column and the "tbl" column is the name of the table to which
** the index belongs. There are usually 10 rows in the sqlite_stat2
** table for each index.
**
** The sqlite_stat2 entires for an index that have sampleno between 0 and 9
** inclusive are samples of the left-most key value in the index taken at
** evenly spaced points along the index. Let the number of samples be S
** (10 in the standard build) and let C be the number of rows in the index.
** Then the sampled rows are given by:
**
** rownumber = (i*C*2 + C)/(S*2)
**
** For i between 0 and S-1. Conceptually, the index space is divided into
** S uniform buckets and the samples are the middle row from each bucket.
**
** The format for sqlite_stat2 is recorded here for legacy reference. This
** version of SQLite does not support sqlite_stat2. It neither reads nor
** writes the sqlite_stat2 table. This version of SQLite only supports
** sqlite_stat3.
**
** Format for sqlite_stat3:
**
** The sqlite_stat3 is an enhancement to sqlite_stat2. A new name is
** used to avoid compatibility problems.
**
** The format of the sqlite_stat3 table is similar to the format for
** the sqlite_stat2 table, with the following changes: (1)
** The sampleno column is removed. (2) Every sample has nEq and nLt
** columns which hold the approximate number of keys in the table that
** exactly match the sample, and which are less than the sample,
** respectively. (3) The number of samples can very from one table
** to the next; the sample count does not have to be exactly 10 as
** it is with sqlite_stat2. (4) The samples do not have to be evenly spaced.
**
** The ANALYZE command will typically generate sqlite_stat3 tables
** that contain between 10 and 40 samples which are distributed across
** the key space, though not uniformly, and which include samples with
** largest possible nEq values.
*/
#ifndef SQLITE_OMIT_ANALYZE
#include "sqliteInt.h"
@@ -42,8 +131,14 @@ static void openStatTable(
const char *zCols;
} aTable[] = {
{ "sqlite_stat1", "tbl,idx,stat" },
#ifdef SQLITE_ENABLE_STAT2
{ "sqlite_stat2", "tbl,idx,sampleno,sample" },
#ifdef SQLITE_ENABLE_STAT3
{ "sqlite_stat3", "tbl,idx,neq,nlt,sample" },
#endif
};
static const char *azToDrop[] = {
"sqlite_stat2",
#ifndef SQLITE_ENABLE_STAT3
"sqlite_stat3",
#endif
};
@@ -59,6 +154,17 @@ static void openStatTable(
assert( sqlite3VdbeDb(v)==db );
pDb = &db->aDb[iDb];
/* Drop all statistics tables that this version of SQLite does not
** understand.
*/
for(i=0; i<ArraySize(azToDrop); i++){
Table *pTab = sqlite3FindTable(db, azToDrop[i], pDb->zName);
if( pTab ) sqlite3CodeDropTable(pParse, pTab, iDb, 0);
}
/* Create new statistic tables if they do not exist, or clear them
** if they do already exist.
*/
for(i=0; i<ArraySize(aTable); i++){
const char *zTab = aTable[i].zName;
Table *pStat;
@@ -89,7 +195,7 @@ static void openStatTable(
}
}
/* Open the sqlite_stat[12] tables for writing. */
/* Open the sqlite_stat[13] tables for writing. */
for(i=0; i<ArraySize(aTable); i++){
sqlite3VdbeAddOp3(v, OP_OpenWrite, iStatCur+i, aRoot[i], iDb);
sqlite3VdbeChangeP4(v, -1, (char *)3, P4_INT32);
@@ -97,6 +203,13 @@ static void openStatTable(
}
}
/*
** Recommended number of samples for sqlite_stat3
*/
#ifndef SQLITE_STAT3_SAMPLES
# define SQLITE_STAT3_SAMPLES 16
#endif
/*
** Generate code to do an analysis of all indices associated with
** a single table.
@@ -119,20 +232,26 @@ static void analyzeOneTable(
int iDb; /* Index of database containing pTab */
int regTabname = iMem++; /* Register containing table name */
int regIdxname = iMem++; /* Register containing index name */
int regSampleno = iMem++; /* Register containing next sample number */
int regCol = iMem++; /* Content of a column analyzed table */
int regStat1 = iMem++; /* The stat column of sqlite_stat1 */
#ifdef SQLITE_ENABLE_STAT3
int regNumEq = iMem-1; /* Number of instances. Same as regStat1 */
int regNumLt = iMem++; /* Number of keys less than regSample */
int regSample = iMem++; /* The next sample value */
int regNext = iMem++; /* Index of next sample to record */
int regSpacing = iMem++; /* Spacing between samples */
int regBigSize = iMem++; /* Always save entries with nEq >= this */
int regTemp1 = iMem++; /* Intermediate register */
int regCount = iMem++; /* Number of rows in the table or index */
int regGosub = iMem++; /* Register holding subroutine return addr */
int once = 1; /* One-time initialization */
int shortJump = 0; /* Instruction address */
int addrStoreStat3 = 0; /* Address of subroutine to wrote to stat3 */
#endif
int regCol = iMem++; /* Content of a column in analyzed table */
int regRec = iMem++; /* Register holding completed record */
int regTemp = iMem++; /* Temporary use register */
int regRowid = iMem++; /* Rowid for the inserted record */
#ifdef SQLITE_ENABLE_STAT2
int addr = 0; /* Instruction address */
int regTemp2 = iMem++; /* Temporary use register */
int regSamplerecno = iMem++; /* Index of next sample to record */
int regRecno = iMem++; /* Current sample index */
int regLast = iMem++; /* Index of last sample to record */
int regFirst = iMem++; /* Index of first sample to record */
#endif
v = sqlite3GetVdbe(pParse);
if( v==0 || NEVER(pTab==0) ){
@@ -165,13 +284,18 @@ static void analyzeOneTable(
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
int nCol;
KeyInfo *pKey;
int addrIfNot; /* address of OP_IfNot */
int *aChngAddr; /* Array of jump instruction addresses */
if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
VdbeNoopComment((v, "Begin analysis of %s", pIdx->zName));
nCol = pIdx->nColumn;
pKey = sqlite3IndexKeyinfo(pParse, pIdx);
if( iMem+1+(nCol*2)>pParse->nMem ){
pParse->nMem = iMem+1+(nCol*2);
}
aChngAddr = sqlite3DbMallocRaw(db, sizeof(int)*pIdx->nColumn);
if( aChngAddr==0 ) continue;
/* Open a cursor to the index to be analyzed. */
assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) );
@@ -182,31 +306,43 @@ static void analyzeOneTable(
/* Populate the register containing the index name. */
sqlite3VdbeAddOp4(v, OP_String8, 0, regIdxname, 0, pIdx->zName, 0);
#ifdef SQLITE_ENABLE_STAT2
#ifdef SQLITE_ENABLE_STAT3
/* If this iteration of the loop is generating code to analyze the
** first index in the pTab->pIndex list, then register regLast has
** not been populated. In this case populate it now. */
if( pTab->pIndex==pIdx ){
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES, regSamplerecno);
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES*2-1, regTemp);
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES*2, regTemp2);
if( once ){
once = 0;
sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regCount);
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_STAT3_SAMPLES, regTemp1);
sqlite3VdbeAddOp3(v, OP_Divide, regTemp1, regCount, regSpacing);
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_STAT3_SAMPLES/2, regTemp1);
sqlite3VdbeAddOp3(v, OP_Divide, regTemp1, regCount, regBigSize);
sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regLast);
sqlite3VdbeAddOp2(v, OP_Null, 0, regFirst);
addr = sqlite3VdbeAddOp3(v, OP_Lt, regSamplerecno, 0, regLast);
sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regLast, regFirst);
sqlite3VdbeAddOp3(v, OP_Multiply, regLast, regTemp, regLast);
sqlite3VdbeAddOp2(v, OP_AddImm, regLast, SQLITE_INDEX_SAMPLES*2-2);
sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regLast, regLast);
sqlite3VdbeJumpHere(v, addr);
/* Generate code for a subroutine that store the most recent sample
** in the sqlite_stat3 table
*/
shortJump = sqlite3VdbeAddOp0(v, OP_Goto);
sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 5, regRec, "bbbbb", 0);
VdbeComment((v, "begin stat3 write subroutine"));
sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regRec, regRowid);
sqlite3VdbeAddOp3(v, OP_Add, regNext, regSpacing, regNext);
sqlite3VdbeAddOp1(v, OP_Return, regGosub);
addrStoreStat3 =
sqlite3VdbeAddOp3(v, OP_Ge, regBigSize, shortJump+1, regNumEq);
sqlite3VdbeAddOp3(v, OP_Add, regNumEq, regNumLt, regTemp1);
sqlite3VdbeAddOp3(v, OP_Ge, regNext, shortJump+1, regTemp1);
sqlite3VdbeAddOp1(v, OP_Return, regGosub);
VdbeComment((v, "end stat3 write subroutine"));
sqlite3VdbeJumpHere(v, shortJump);
}
/* Reset state registers */
sqlite3VdbeAddOp2(v, OP_Copy, regSpacing, regNext);
sqlite3VdbeAddOp2(v, OP_Integer, 0, regNumEq);
sqlite3VdbeAddOp2(v, OP_Integer, 0, regNumLt);
/* Zero the regSampleno and regRecno registers. */
sqlite3VdbeAddOp2(v, OP_Integer, 0, regSampleno);
sqlite3VdbeAddOp2(v, OP_Integer, 0, regRecno);
sqlite3VdbeAddOp2(v, OP_Copy, regFirst, regSamplerecno);
#endif
#endif /* SQLITE_ENABLE_STAT3 */
/* The block of memory cells initialized here is used as follows.
**
@@ -236,75 +372,54 @@ static void analyzeOneTable(
endOfLoop = sqlite3VdbeMakeLabel(v);
sqlite3VdbeAddOp2(v, OP_Rewind, iIdxCur, endOfLoop);
topOfLoop = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_AddImm, iMem, 1);
sqlite3VdbeAddOp2(v, OP_AddImm, iMem, 1); /* Increment row counter */
for(i=0; i<nCol; i++){
CollSeq *pColl;
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regCol);
if( i==0 ){
#ifdef SQLITE_ENABLE_STAT2
/* Check if the record that cursor iIdxCur points to contains a
** value that should be stored in the sqlite_stat2 table. If so,
** store it. */
int ne = sqlite3VdbeAddOp3(v, OP_Ne, regRecno, 0, regSamplerecno);
assert( regTabname+1==regIdxname
&& regTabname+2==regSampleno
&& regTabname+3==regCol
);
sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 4, regRec, "aaab", 0);
sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regRec, regRowid);
/* Calculate new values for regSamplerecno and regSampleno.
**
** sampleno = sampleno + 1
** samplerecno = samplerecno+(remaining records)/(remaining samples)
*/
sqlite3VdbeAddOp2(v, OP_AddImm, regSampleno, 1);
sqlite3VdbeAddOp3(v, OP_Subtract, regRecno, regLast, regTemp);
sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES, regTemp2);
sqlite3VdbeAddOp3(v, OP_Subtract, regSampleno, regTemp2, regTemp2);
sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regTemp, regTemp);
sqlite3VdbeAddOp3(v, OP_Add, regSamplerecno, regTemp, regSamplerecno);
sqlite3VdbeJumpHere(v, ne);
sqlite3VdbeAddOp2(v, OP_AddImm, regRecno, 1);
#endif
/* Always record the very first row */
sqlite3VdbeAddOp1(v, OP_IfNot, iMem+1);
addrIfNot = sqlite3VdbeAddOp1(v, OP_IfNot, iMem+1);
}
assert( pIdx->azColl!=0 );
assert( pIdx->azColl[i]!=0 );
pColl = sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
sqlite3VdbeAddOp4(v, OP_Ne, regCol, 0, iMem+nCol+i+1,
(char*)pColl, P4_COLLSEQ);
aChngAddr[i] = sqlite3VdbeAddOp4(v, OP_Ne, regCol, 0, iMem+nCol+i+1,
(char*)pColl, P4_COLLSEQ);
sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
}
if( db->mallocFailed ){
/* If a malloc failure has occurred, then the result of the expression
** passed as the second argument to the call to sqlite3VdbeJumpHere()
** below may be negative. Which causes an assert() to fail (or an
** out-of-bounds write if SQLITE_DEBUG is not defined). */
return;
VdbeComment((v, "jump if column %d changed", i));
#ifdef SQLITE_ENABLE_STAT3
if( i==0 && addrStoreStat3 ){
sqlite3VdbeAddOp2(v, OP_AddImm, regNumEq, 1);
VdbeComment((v, "incr repeat count"));
}
#endif
}
sqlite3VdbeAddOp2(v, OP_Goto, 0, endOfLoop);
for(i=0; i<nCol; i++){
int addr2 = sqlite3VdbeCurrentAddr(v) - (nCol*2);
sqlite3VdbeJumpHere(v, aChngAddr[i]); /* Set jump dest for the OP_Ne */
if( i==0 ){
sqlite3VdbeJumpHere(v, addr2-1); /* Set jump dest for the OP_IfNot */
sqlite3VdbeJumpHere(v, addrIfNot); /* Jump dest for OP_IfNot */
#ifdef SQLITE_ENABLE_STAT3
sqlite3VdbeAddOp2(v, OP_Gosub, regGosub, addrStoreStat3);
sqlite3VdbeAddOp2(v, OP_Copy, regCol, regSample);
sqlite3VdbeAddOp3(v, OP_Add, regNumEq, regNumLt, regNumLt);
sqlite3VdbeAddOp2(v, OP_Integer, 1, regNumEq);
#endif
}
sqlite3VdbeJumpHere(v, addr2); /* Set jump dest for the OP_Ne */
sqlite3VdbeAddOp2(v, OP_AddImm, iMem+i+1, 1);
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, iMem+nCol+i+1);
}
sqlite3DbFree(db, aChngAddr);
/* End of the analysis loop. */
/* Always jump here after updating the iMem+1...iMem+1+nCol counters */
sqlite3VdbeResolveLabel(v, endOfLoop);
sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, topOfLoop);
sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
#ifdef SQLITE_ENABLE_STAT3
sqlite3VdbeAddOp2(v, OP_Gosub, regGosub, addrStoreStat3);
#endif
/* Store the results in sqlite_stat1.
**
@@ -324,18 +439,18 @@ static void analyzeOneTable(
** If K>0 then it is always the case the D>0 so division by zero
** is never possible.
*/
sqlite3VdbeAddOp2(v, OP_SCopy, iMem, regSampleno);
sqlite3VdbeAddOp2(v, OP_SCopy, iMem, regStat1);
if( jZeroRows<0 ){
jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, iMem);
}
for(i=0; i<nCol; i++){
sqlite3VdbeAddOp4(v, OP_String8, 0, regTemp, 0, " ", 0);
sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regStat1, regStat1);
sqlite3VdbeAddOp3(v, OP_Add, iMem, iMem+i+1, regTemp);
sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
sqlite3VdbeAddOp3(v, OP_Divide, iMem+i+1, regTemp, regTemp);
sqlite3VdbeAddOp1(v, OP_ToInt, regTemp);
sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regStat1, regStat1);
}
sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regRowid);
@@ -349,9 +464,9 @@ static void analyzeOneTable(
if( pTab->pIndex==0 ){
sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pTab->tnum, iDb);
VdbeComment((v, "%s", pTab->zName));
sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regSampleno);
sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regStat1);
sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regSampleno);
jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regStat1);
}else{
sqlite3VdbeJumpHere(v, jZeroRows);
jZeroRows = sqlite3VdbeAddOp0(v, OP_Goto);
@@ -365,6 +480,7 @@ static void analyzeOneTable(
sqlite3VdbeJumpHere(v, jZeroRows);
}
/*
** Generate code that will cause the most recent index analysis to
** be loaded into internal hash tables where is can be used.
@@ -518,7 +634,7 @@ static int analysisLoader(void *pData, int argc, char **argv, char **NotUsed){
Index *pIndex;
Table *pTable;
int i, c, n;
unsigned int v;
tRowcnt v;
const char *z;
assert( argc==3 );
@@ -561,36 +677,157 @@ static int analysisLoader(void *pData, int argc, char **argv, char **NotUsed){
** and its contents.
*/
void sqlite3DeleteIndexSamples(sqlite3 *db, Index *pIdx){
#ifdef SQLITE_ENABLE_STAT2
#ifdef SQLITE_ENABLE_STAT3
if( pIdx->aSample ){
int j;
for(j=0; j<SQLITE_INDEX_SAMPLES; j++){
for(j=0; j<pIdx->nSample; j++){
IndexSample *p = &pIdx->aSample[j];
if( p->eType==SQLITE_TEXT || p->eType==SQLITE_BLOB ){
sqlite3DbFree(db, p->u.z);
sqlite3_free(p->u.z);
}
}
sqlite3DbFree(db, pIdx->aSample);
sqlite3_free(pIdx->aSample);
}
pIdx->nSample = 0;
pIdx->aSample = 0;
#else
UNUSED_PARAMETER(db);
UNUSED_PARAMETER(pIdx);
#endif
}
#ifdef SQLITE_ENABLE_STAT3
/*
** Load the content of the sqlite_stat1 and sqlite_stat2 tables. The
** Load content from the sqlite_stat3 table into the Index.aSample[]
** arrays of all indices.
*/
static int loadStat3(sqlite3 *db, const char *zDb){
int rc; /* Result codes from subroutines */
sqlite3_stmt *pStmt = 0; /* An SQL statement being run */
char *zSql; /* Text of the SQL statement */
Index *pPrevIdx = 0; /* Previous index in the loop */
int idx; /* slot in pIdx->aSample[] for next sample */
int eType; /* Datatype of a sample */
IndexSample *pSample; /* A slot in pIdx->aSample[] */
if( !sqlite3FindTable(db, "sqlite_stat3", zDb) ){
return SQLITE_OK;
}
zSql = sqlite3MPrintf(db,
"SELECT idx,count(*) FROM %Q.sqlite_stat3"
" GROUP BY idx", zDb);
if( !zSql ){
return SQLITE_NOMEM;
}
rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
sqlite3DbFree(db, zSql);
if( rc ) return rc;
while( sqlite3_step(pStmt)==SQLITE_ROW ){
char *zIndex; /* Index name */
Index *pIdx; /* Pointer to the index object */
int nSample; /* Number of samples */
zIndex = (char *)sqlite3_column_text(pStmt, 0);
if( zIndex==0 ) continue;
nSample = sqlite3_column_int(pStmt, 1);
if( nSample>255 ) continue;
pIdx = sqlite3FindIndex(db, zIndex, zDb);
if( pIdx==0 ) continue;
assert( pIdx->nSample==0 );
pIdx->nSample = (u8)nSample;
pIdx->aSample = sqlite3MallocZero( nSample*sizeof(IndexSample) );
if( pIdx->aSample==0 ){
db->mallocFailed = 1;
sqlite3_finalize(pStmt);
return SQLITE_NOMEM;
}
}
sqlite3_finalize(pStmt);
zSql = sqlite3MPrintf(db,
"SELECT idx,nlt,neq,sample FROM %Q.sqlite_stat3"
" ORDER BY idx, nlt", zDb);
if( !zSql ){
return SQLITE_NOMEM;
}
rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
sqlite3DbFree(db, zSql);
if( rc ) return rc;
while( sqlite3_step(pStmt)==SQLITE_ROW ){
char *zIndex; /* Index name */
Index *pIdx; /* Pointer to the index object */
zIndex = (char *)sqlite3_column_text(pStmt, 0);
if( zIndex==0 ) continue;
pIdx = sqlite3FindIndex(db, zIndex, zDb);
if( pIdx==0 ) continue;
if( pIdx==pPrevIdx ){
idx++;
}else{
pPrevIdx = pIdx;
idx = 0;
}
assert( idx<pIdx->nSample );
pSample = &pIdx->aSample[idx];
pSample->nLt = (tRowcnt)sqlite3_column_int64(pStmt, 1);
pSample->nEq = (tRowcnt)sqlite3_column_int64(pStmt, 2);
eType = sqlite3_column_type(pStmt, 3);
pSample->eType = (u8)eType;
switch( eType ){
case SQLITE_INTEGER: {
pSample->u.i = sqlite3_column_int64(pStmt, 3);
break;
}
case SQLITE_FLOAT: {
pSample->u.r = sqlite3_column_double(pStmt, 3);
break;
}
case SQLITE_NULL: {
break;
}
default: assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB ); {
const char *z = (const char *)(
(eType==SQLITE_BLOB) ?
sqlite3_column_blob(pStmt, 3):
sqlite3_column_text(pStmt, 3)
);
int n = sqlite3_column_bytes(pStmt, 2);
if( n>0xffff ) n = 0xffff;
pSample->nByte = (u16)n;
if( n < 1){
pSample->u.z = 0;
}else{
pSample->u.z = sqlite3Malloc(n);
if( pSample->u.z==0 ){
db->mallocFailed = 1;
sqlite3_finalize(pStmt);
return SQLITE_NOMEM;
}
memcpy(pSample->u.z, z, n);
}
}
}
}
return sqlite3_finalize(pStmt);
}
#endif /* SQLITE_ENABLE_STAT3 */
/*
** Load the content of the sqlite_stat1 and sqlite_stat3 tables. The
** contents of sqlite_stat1 are used to populate the Index.aiRowEst[]
** arrays. The contents of sqlite_stat2 are used to populate the
** arrays. The contents of sqlite_stat3 are used to populate the
** Index.aSample[] arrays.
**
** If the sqlite_stat1 table is not present in the database, SQLITE_ERROR
** is returned. In this case, even if SQLITE_ENABLE_STAT2 was defined
** during compilation and the sqlite_stat2 table is present, no data is
** is returned. In this case, even if SQLITE_ENABLE_STAT3 was defined
** during compilation and the sqlite_stat3 table is present, no data is
** read from it.
**
** If SQLITE_ENABLE_STAT2 was defined during compilation and the
** sqlite_stat2 table is not present in the database, SQLITE_ERROR is
** If SQLITE_ENABLE_STAT3 was defined during compilation and the
** sqlite_stat3 table is not present in the database, SQLITE_ERROR is
** returned. However, in this case, data is read from the sqlite_stat1
** table (if it is present) before returning.
**
@@ -612,8 +849,10 @@ int sqlite3AnalysisLoad(sqlite3 *db, int iDb){
for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
Index *pIdx = sqliteHashData(i);
sqlite3DefaultRowEst(pIdx);
#ifdef SQLITE_ENABLE_STAT3
sqlite3DeleteIndexSamples(db, pIdx);
pIdx->aSample = 0;
#endif
}
/* Check to make sure the sqlite_stat1 table exists */
@@ -625,7 +864,7 @@ int sqlite3AnalysisLoad(sqlite3 *db, int iDb){
/* Load new statistics out of the sqlite_stat1 table */
zSql = sqlite3MPrintf(db,
"SELECT tbl, idx, stat FROM %Q.sqlite_stat1", sInfo.zDatabase);
"SELECT tbl,idx,stat FROM %Q.sqlite_stat1", sInfo.zDatabase);
if( zSql==0 ){
rc = SQLITE_NOMEM;
}else{
@@ -634,78 +873,10 @@ int sqlite3AnalysisLoad(sqlite3 *db, int iDb){
}
/* Load the statistics from the sqlite_stat2 table. */
#ifdef SQLITE_ENABLE_STAT2
if( rc==SQLITE_OK && !sqlite3FindTable(db, "sqlite_stat2", sInfo.zDatabase) ){
rc = SQLITE_ERROR;
}
/* Load the statistics from the sqlite_stat3 table. */
#ifdef SQLITE_ENABLE_STAT3
if( rc==SQLITE_OK ){
sqlite3_stmt *pStmt = 0;
zSql = sqlite3MPrintf(db,
"SELECT idx,sampleno,sample FROM %Q.sqlite_stat2", sInfo.zDatabase);
if( !zSql ){
rc = SQLITE_NOMEM;
}else{
rc = sqlite3_prepare(db, zSql, -1, &pStmt, 0);
sqlite3DbFree(db, zSql);
}
if( rc==SQLITE_OK ){
while( sqlite3_step(pStmt)==SQLITE_ROW ){
char *zIndex; /* Index name */
Index *pIdx; /* Pointer to the index object */
zIndex = (char *)sqlite3_column_text(pStmt, 0);
pIdx = zIndex ? sqlite3FindIndex(db, zIndex, sInfo.zDatabase) : 0;
if( pIdx ){
int iSample = sqlite3_column_int(pStmt, 1);
if( iSample<SQLITE_INDEX_SAMPLES && iSample>=0 ){
int eType = sqlite3_column_type(pStmt, 2);
if( pIdx->aSample==0 ){
static const int sz = sizeof(IndexSample)*SQLITE_INDEX_SAMPLES;
pIdx->aSample = (IndexSample *)sqlite3DbMallocRaw(0, sz);
if( pIdx->aSample==0 ){
db->mallocFailed = 1;
break;
}
memset(pIdx->aSample, 0, sz);
}
assert( pIdx->aSample );
{
IndexSample *pSample = &pIdx->aSample[iSample];
pSample->eType = (u8)eType;
if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
pSample->u.r = sqlite3_column_double(pStmt, 2);
}else if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
const char *z = (const char *)(
(eType==SQLITE_BLOB) ?
sqlite3_column_blob(pStmt, 2):
sqlite3_column_text(pStmt, 2)
);
int n = sqlite3_column_bytes(pStmt, 2);
if( n>24 ){
n = 24;
}
pSample->nByte = (u8)n;
if( n < 1){
pSample->u.z = 0;
}else{
pSample->u.z = sqlite3DbStrNDup(0, z, n);
if( pSample->u.z==0 ){
db->mallocFailed = 1;
break;
}
}
}
}
}
}
}
rc = sqlite3_finalize(pStmt);
}
rc = loadStat3(db, sInfo.zDatabase);
}
#endif