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Add the sqlite_stat3.nDLT field. Use an linear congruence PRNG to choose

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which samples to select from among those with the same nEq field.

FossilOrigin-Name: 1dcd24283e6c1cc638eb9ffac434046447f88769
This commit is contained in:
drh
2011-08-13 15:25:10 +00:00
parent ade3addfb5
commit f404c86ad7
3 changed files with 45 additions and 33 deletions
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64
src/analyze.c
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@@ -19,7 +19,7 @@
**
** CREATE TABLE sqlite_stat1(tbl, idx, stat);
** CREATE TABLE sqlite_stat2(tbl, idx, sampleno, sample);
** CREATE TABLE sqlite_stat3(tbl, idx, nLt, nEq, sample);
** CREATE TABLE sqlite_stat3(tbl, idx, nEq, nLt, nDLt, sample);
**
** Additional tables might be added in future releases of SQLite.
** The sqlite_stat2 table is not created or used unless the SQLite version
@@ -88,12 +88,13 @@
**
** 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 sampleno column is removed. (2) Every sample has nEq, nLt, and nDLt
** columns which hold the approximate number of rows in the table that
** exactly match the sample, the approximate number of rows with values
** less than the sample, and the approximate number of distinct key values
** 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.
**
** The ANALYZE command will typically generate sqlite_stat3 tables
** that contain between 10 and 40 samples which are distributed across
@@ -132,7 +133,7 @@ static void openStatTable(
} aTable[] = {
{ "sqlite_stat1", "tbl,idx,stat" },
#ifdef SQLITE_ENABLE_STAT3
{ "sqlite_stat3", "tbl,idx,neq,nlt,sample" },
{ "sqlite_stat3", "tbl,idx,neq,nlt,ndlt,sample" },
#endif
};
static const char *azToDrop[] = {
@@ -207,7 +208,7 @@ static void openStatTable(
** Recommended number of samples for sqlite_stat3
*/
#ifndef SQLITE_STAT3_SAMPLES
# define SQLITE_STAT3_SAMPLES 20
# define SQLITE_STAT3_SAMPLES 24
#endif
/*
@@ -222,10 +223,12 @@ struct Stat3Accum {
int iMin; /* Index of entry with minimum nEq and hash */
int mxSample; /* Maximum number of samples to accumulate */
int nSample; /* Current number of samples */
u32 iPrn; /* Pseudo-random number used for sampling */
struct Stat3Sample {
i64 iRowid; /* Rowid in main table of the key */
tRowcnt nEq; /* sqlite_stat3.nEq */
tRowcnt nLt; /* sqlite_stat3.nLt */
tRowcnt nDLt; /* sqlite_stat3.nDLt */
u8 isPSample; /* True if a periodic sample */
u32 iHash; /* Tiebreaker hash */
} *a; /* An array of samples */
@@ -263,7 +266,8 @@ static void stat3Init(
p->a = (struct Stat3Sample*)&p[1];
p->nRow = nRow;
p->mxSample = mxSample;
p->nPSample = p->nRow/6 + 1;
p->nPSample = p->nRow/(mxSample/3+1) + 1;
sqlite3_randomness(sizeof(p->iPrn), &p->iPrn);
sqlite3_result_blob(context, p, sizeof(p), sqlite3_free);
}
static const FuncDef stat3InitFuncdef = {
@@ -282,7 +286,7 @@ static const FuncDef stat3InitFuncdef = {
/*
** Implementation of the stat3_push(nEq,nLt,rowid,P) SQL function. The
** Implementation of the stat3_push(nEq,nLt,nDLt,rowid,P) SQL function. The
** arguments describe a single key instance. This routine makes the
** decision about whether or not to retain this key for the sqlite_stat3
** table.
@@ -294,23 +298,20 @@ static void stat3Push(
int argc,
sqlite3_value **argv
){
Stat3Accum *p = (Stat3Accum*)sqlite3_value_blob(argv[3]);
Stat3Accum *p = (Stat3Accum*)sqlite3_value_blob(argv[4]);
tRowcnt nEq = sqlite3_value_int64(argv[0]);
tRowcnt nLt = sqlite3_value_int64(argv[1]);
i64 rowid = sqlite3_value_int64(argv[2]);
tRowcnt nDLt = sqlite3_value_int64(argv[2]);
i64 rowid = sqlite3_value_int64(argv[3]);
u8 isPSample = 0;
u8 doInsert = 0;
int iMin = p->iMin;
struct Stat3Sample *pSample;
int i;
u32 h, h1, h2, h3;
u32 h;
if( nEq==0 ) return;
h1 = (unsigned)(rowid&0xffff);
h2 = (unsigned)nEq;
h3 = (unsigned)(nLt+1);
h = h1*h2*h3*0x10010001;
h = p->iPrn = p->iPrn*1103515245 + 12345;
if( (nLt/p->nPSample)!=((nEq+nLt)/p->nPSample) ){
doInsert = isPSample = 1;
}else if( p->nSample<p->mxSample ){
@@ -322,13 +323,17 @@ static void stat3Push(
}
if( !doInsert ) return;
if( p->nSample==p->mxSample ){
pSample = &p->a[iMin];
if( iMin<p->nSample ){
memcpy(&p->a[iMin], &p->a[iMin+1], sizeof(p->a[0])*(p->nSample-iMin));
}
pSample = &p->a[p->nSample-1];
}else{
pSample = &p->a[p->nSample++];
}
pSample->iRowid = rowid;
pSample->nEq = nEq;
pSample->nLt = nLt;
pSample->nDLt = nDLt;
pSample->iHash = h;
pSample->isPSample = isPSample;
@@ -358,7 +363,7 @@ static void stat3Push(
}
}
static const FuncDef stat3PushFuncdef = {
3, /* nArg */
5, /* nArg */
SQLITE_UTF8, /* iPrefEnc */
0, /* flags */
0, /* pUserData */
@@ -380,6 +385,7 @@ static const FuncDef stat3PushFuncdef = {
** argc==2 result: rowid
** argc==3 result: nEq
** argc==4 result: nLt
** argc==5 result: nDLt
*/
static void stat3Get(
sqlite3_context *context,
@@ -395,6 +401,7 @@ static void stat3Get(
case 2: sqlite3_result_int64(context, p->a[n].iRowid); break;
case 3: sqlite3_result_int64(context, p->a[n].nEq); break;
case 4: sqlite3_result_int64(context, p->a[n].nLt); break;
case 5: sqlite3_result_int64(context, p->a[n].nDLt); break;
}
}
static const FuncDef stat3GetFuncdef = {
@@ -441,6 +448,7 @@ static void analyzeOneTable(
#ifdef SQLITE_ENABLE_STAT3
int regNumEq = regStat1; /* Number of instances. Same as regStat1 */
int regNumLt = iMem++; /* Number of keys less than regSample */
int regNumDLt = iMem++; /* Number of distinct keys less than regSample */
int regSample = iMem++; /* The next sample value */
int regRowid = regSample; /* Rowid of a sample */
int regAccum = iMem++; /* Register to hold Stat3Accum object */
@@ -520,6 +528,7 @@ static void analyzeOneTable(
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_STAT3_SAMPLES, regTemp1);
sqlite3VdbeAddOp2(v, OP_Integer, 0, regNumEq);
sqlite3VdbeAddOp2(v, OP_Integer, 0, regNumLt);
sqlite3VdbeAddOp2(v, OP_Integer, -1, regNumDLt);
sqlite3VdbeAddOp4(v, OP_Function, 1, regCount, regAccum,
(char*)&stat3InitFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 2);
@@ -584,9 +593,10 @@ static void analyzeOneTable(
#ifdef SQLITE_ENABLE_STAT3
sqlite3VdbeAddOp4(v, OP_Function, 1, regNumEq, regTemp2,
(char*)&stat3PushFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 4);
sqlite3VdbeChangeP5(v, 5);
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, pIdx->nColumn, regRowid);
sqlite3VdbeAddOp3(v, OP_Add, regNumEq, regNumLt, regNumLt);
sqlite3VdbeAddOp2(v, OP_AddImm, regNumDLt, 1);
sqlite3VdbeAddOp2(v, OP_Integer, 1, regNumEq);
#endif
}
@@ -603,7 +613,7 @@ static void analyzeOneTable(
#ifdef SQLITE_ENABLE_STAT3
sqlite3VdbeAddOp4(v, OP_Function, 1, regNumEq, regTemp2,
(char*)&stat3PushFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 4);
sqlite3VdbeChangeP5(v, 5);
sqlite3VdbeAddOp2(v, OP_Integer, -1, regLoop);
shortJump =
sqlite3VdbeAddOp2(v, OP_AddImm, regLoop, 1);
@@ -620,7 +630,10 @@ static void analyzeOneTable(
sqlite3VdbeAddOp4(v, OP_Function, 1, regAccum, regNumLt,
(char*)&stat3GetFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 4);
sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 5, regRec, "bbbbb", 0);
sqlite3VdbeAddOp4(v, OP_Function, 1, regAccum, regNumDLt,
(char*)&stat3GetFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 5);
sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 6, regRec, "bbbbbb", 0);
sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regNewRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regRec, regNewRowid);
sqlite3VdbeAddOp2(v, OP_Goto, 0, shortJump);
@@ -953,8 +966,7 @@ static int loadStat3(sqlite3 *db, const char *zDb){
sqlite3_finalize(pStmt);
zSql = sqlite3MPrintf(db,
"SELECT idx,nlt,neq,sample FROM %Q.sqlite_stat3"
" ORDER BY idx, nlt", zDb);
"SELECT idx,nlt,neq,sample FROM %Q.sqlite_stat3", zDb);
if( !zSql ){
return SQLITE_NOMEM;
}