/*
** 2005 July 8
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** 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, 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
** is between 3.6.18 and 3.7.8, inclusive, and unless SQLite is compiled
** with SQLITE_ENABLE_STAT2. The sqlite_stat2 table is deprecated.
** The sqlite_stat2 table is superseded by sqlite_stat3, which is only
** created and used by SQLite versions 3.7.9 and later and 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 3.7.8. 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 entries 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 of
** the sqlite_stat2 table. There are multiple entries for each index.
** The idx column names the index and the tbl column is the table of the
** index. If the idx and tbl columns are the same, then the sample is
** of the INTEGER PRIMARY KEY. The sample column is a value taken from
** the left-most column of the index. The nEq column is the approximate
** number of entires in the index whose left-most column exactly matches
** the sample. nLt is the approximate number of entires whose left-most
** column is less than the sample. The nDLt column is the approximate
** number of distinct left-most entries in the index that are less than
** the sample.
**
** Future versions of SQLite might change to store a string containing
** multiple integers values in the nDLt column of sqlite_stat3. The first
** integer will be the number of prior index entires that are distinct in
** the left-most column. The second integer will be the number of prior index
** entries that are distinct in the first two columns. The third integer
** will be the number of prior index entries that are distinct in the first
** three columns. And so forth. With that extension, the nDLt field is
** similar in function to the sqlite_stat1.stat field.
**
** There can be an arbitrary number of sqlite_stat3 entries per index.
** 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"
/*
** This routine generates code that opens the sqlite_stat1 table for
** writing with cursor iStatCur. If the library was built with the
** SQLITE_ENABLE_STAT4 macro defined, then the sqlite_stat4 table is
** opened for writing using cursor (iStatCur+1)
**
** If the sqlite_stat1 tables does not previously exist, it is created.
** Similarly, if the sqlite_stat4 table does not exist and the library
** is compiled with SQLITE_ENABLE_STAT4 defined, it is created.
**
** Argument zWhere may be a pointer to a buffer containing a table name,
** or it may be a NULL pointer. If it is not NULL, then all entries in
** the sqlite_stat1 and (if applicable) sqlite_stat4 tables associated
** with the named table are deleted. If zWhere==0, then code is generated
** to delete all stat table entries.
*/
static void openStatTable(
Parse *pParse, /* Parsing context */
int iDb, /* The database we are looking in */
int iStatCur, /* Open the sqlite_stat1 table on this cursor */
const char *zWhere, /* Delete entries for this table or index */
const char *zWhereType /* Either "tbl" or "idx" */
){
static const struct {
const char *zName;
const char *zCols;
} aTable[] = {
{ "sqlite_stat1", "tbl,idx,stat" },
#ifdef SQLITE_ENABLE_STAT4
{ "sqlite_stat4", "tbl,idx,neq,nlt,ndlt,sample" },
#endif
};
int aRoot[] = {0, 0};
u8 aCreateTbl[] = {0, 0};
int i;
sqlite3 *db = pParse->db;
Db *pDb;
Vdbe *v = sqlite3GetVdbe(pParse);
if( v==0 ) return;
assert( sqlite3BtreeHoldsAllMutexes(db) );
assert( sqlite3VdbeDb(v)==db );
pDb = &db->aDb[iDb];
/* 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;
if( (pStat = sqlite3FindTable(db, zTab, pDb->zName))==0 ){
/* The sqlite_stat[12] table does not exist. Create it. Note that a
** side-effect of the CREATE TABLE statement is to leave the rootpage
** of the new table in register pParse->regRoot. This is important
** because the OpenWrite opcode below will be needing it. */
sqlite3NestedParse(pParse,
"CREATE TABLE %Q.%s(%s)", pDb->zName, zTab, aTable[i].zCols
);
aRoot[i] = pParse->regRoot;
aCreateTbl[i] = OPFLAG_P2ISREG;
}else{
/* The table already exists. If zWhere is not NULL, delete all entries
** associated with the table zWhere. If zWhere is NULL, delete the
** entire contents of the table. */
aRoot[i] = pStat->tnum;
sqlite3TableLock(pParse, iDb, aRoot[i], 1, zTab);
if( zWhere ){
sqlite3NestedParse(pParse,
"DELETE FROM %Q.%s WHERE %s=%Q", pDb->zName, zTab, zWhereType, zWhere
);
}else{
/* The sqlite_stat[12] table already exists. Delete all rows. */
sqlite3VdbeAddOp2(v, OP_Clear, aRoot[i], iDb);
}
}
}
/* Open the sqlite_stat[14] 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);
sqlite3VdbeChangeP5(v, aCreateTbl[i]);
}
}
/*
** Recommended number of samples for sqlite_stat4
*/
#ifndef SQLITE_STAT4_SAMPLES
# define SQLITE_STAT4_SAMPLES 24
#endif
/*
** Three SQL functions - stat4_init(), stat4_push(), and stat4_pop() -
** share an instance of the following structure to hold their state
** information.
*/
typedef struct Stat4Accum Stat4Accum;
struct Stat4Accum {
tRowcnt nRow; /* Number of rows in the entire table */
tRowcnt nPSample; /* How often to do a periodic sample */
int iMin; /* Index of entry with minimum nSumEq and hash */
int mxSample; /* Maximum number of samples to accumulate */
int nSample; /* Current number of samples */
int nCol; /* Number of columns in the index */
u32 iPrn; /* Pseudo-random number used for sampling */
struct Stat4Sample {
i64 iRowid; /* Rowid in main table of the key */
tRowcnt nSumEq; /* Sum of anEq[] values */
tRowcnt *anEq; /* sqlite_stat4.nEq */
tRowcnt *anLt; /* sqlite_stat4.nLt */
tRowcnt *anDLt; /* sqlite_stat4.nDLt */
u8 isPSample; /* True if a periodic sample */
u32 iHash; /* Tiebreaker hash */
} *a; /* An array of samples */
};
#ifdef SQLITE_ENABLE_STAT4
/*
** Implementation of the stat4_init(C,N,S) SQL function. The three parameters
** are the number of rows in the table or index (C), the number of columns
** in the index (N) and the number of samples to accumulate (S).
**
** 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.
** the size of the blob is sizeof(void*) bytes).
*/
static void stat4Init(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
Stat4Accum *p;
u8 *pSpace; /* Allocated space not yet assigned */
tRowcnt nRow; /* Number of rows in table (C) */
int mxSample; /* Maximum number of samples collected */
int nCol; /* Number of columns in index being sampled */
int n; /* Bytes of space to allocate */
int i; /* Used to iterate through p->aSample[] */
/* Decode the three function arguments */
UNUSED_PARAMETER(argc);
nRow = (tRowcnt)sqlite3_value_int64(argv[0]);
nCol = sqlite3_value_int(argv[1]);
mxSample = sqlite3_value_int(argv[2]);
assert( nCol>0 );
/* Allocate the space required for the Stat4Accum object */
n = sizeof(*p) + (sizeof(p->a[0]) + 3*sizeof(tRowcnt)*nCol)*mxSample;
p = sqlite3MallocZero( n );
if( p==0 ){
sqlite3_result_error_nomem(context);
return;
}
/* Populate the new Stat4Accum object */
p->nRow = nRow;
p->nCol = nCol;
p->mxSample = mxSample;
p->nPSample = p->nRow/(mxSample/3+1) + 1;
sqlite3_randomness(sizeof(p->iPrn), &p->iPrn);
p->a = (struct Stat4Sample*)&p[1];
pSpace = (u8*)(&p->a[mxSample]);
for(i=0; i<mxSample; i++){
p->a[i].anEq = (tRowcnt *)pSpace; pSpace += (sizeof(tRowcnt) * nCol);
p->a[i].anLt = (tRowcnt *)pSpace; pSpace += (sizeof(tRowcnt) * nCol);
p->a[i].anDLt = (tRowcnt *)pSpace; pSpace += (sizeof(tRowcnt) * nCol);
}
assert( (pSpace - (u8*)p)==n );
/* Return a pointer to the allocated object to the caller */
sqlite3_result_blob(context, p, sizeof(p), sqlite3_free);
}
static const FuncDef stat4InitFuncdef = {
3, /* nArg */
SQLITE_UTF8, /* iPrefEnc */
0, /* flags */
0, /* pUserData */
0, /* pNext */
stat4Init, /* xFunc */
0, /* xStep */
0, /* xFinalize */
"stat4_init", /* zName */
0, /* pHash */
0 /* pDestructor */
};
/*
** Implementation of the stat4_push 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_stat4 table.
**
** The calling convention is:
**
** stat4_push(P, rowid, ...nEq args..., ...nLt args..., ...nDLt args...)
**
** where each instance of the "...nXX args..." is replaced by an array of
** nCol arguments, where nCol is the number of columns in the index being
** sampled (if the index being sampled is "CREATE INDEX i ON t(a, b)", a
** total of 8 arguments are passed when this function is invoked).
**
** The return value is always NULL.
*/
static void stat4Push(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
Stat4Accum *p = (Stat4Accum*)sqlite3_value_blob(argv[0]);
i64 rowid = sqlite3_value_int64(argv[1]);
i64 nSumEq = 0; /* Sum of all nEq parameters */
struct Stat4Sample *pSample;
u32 h;
int iMin = p->iMin;
int i;
u8 isPSample = 0;
u8 doInsert = 0;
sqlite3_value **aEq = &argv[2];
sqlite3_value **aLt = &argv[2+p->nCol];
sqlite3_value **aDLt = &argv[2+p->nCol+p->nCol];
i64 nEq = sqlite3_value_int64(aEq[p->nCol-1]);
i64 nLt = sqlite3_value_int64(aLt[p->nCol-1]);
UNUSED_PARAMETER(context);
UNUSED_PARAMETER(argc);
assert( p->nCol>0 );
assert( argc==(2 + 3*p->nCol) );
/* Set nSumEq to the sum of all nEq parameters. */
for(i=0; i<p->nCol; i++){
nSumEq += sqlite3_value_int64(aEq[i]);
}
if( nSumEq==0 ) return;
/* Figure out if this sample will be used. Set isPSample to true if this
** is a periodic sample, or false if it is being captured because of a
** large nSumEq value. If the sample will not be used, return early. */
h = p->iPrn = p->iPrn*1103515245 + 12345;
if( (nLt/p->nPSample)!=((nEq+nLt)/p->nPSample) ){
doInsert = isPSample = 1;
}else if( (p->nSample<p->mxSample)
|| (nSumEq>p->a[iMin].nSumEq)
|| (nSumEq==p->a[iMin].nSumEq && h>p->a[iMin].iHash)
){
doInsert = 1;
}
if( !doInsert ) return;
/* Fill in the new Stat4Sample object. */
if( p->nSample==p->mxSample ){
struct Stat4Sample *pMin = &p->a[iMin];
tRowcnt *anEq = pMin->anEq;
tRowcnt *anDLt = pMin->anDLt;
tRowcnt *anLt = pMin->anLt;
assert( p->nSample - iMin - 1 >= 0 );
memmove(pMin, &pMin[1], sizeof(p->a[0])*(p->nSample-iMin-1));
pSample = &p->a[p->nSample-1];
pSample->anEq = anEq;
pSample->anDLt = anDLt;
pSample->anLt = anLt;
}else{
pSample = &p->a[p->nSample++];
}
pSample->iRowid = rowid;
pSample->iHash = h;
pSample->isPSample = isPSample;
pSample->nSumEq = nSumEq;
for(i=0; i<p->nCol; i++){
pSample->anEq[i] = sqlite3_value_int64(aEq[i]);
pSample->anLt[i] = sqlite3_value_int64(aLt[i]);
pSample->anDLt[i] = sqlite3_value_int64(aDLt[i]);
}
/* Find the new minimum */
if( p->nSample==p->mxSample ){
u32 iHash = 0; /* Hash corresponding to iMin/nSumEq entry */
i64 nMinEq = LARGEST_INT64; /* Smallest nSumEq seen so far */
assert( iMin = -1 );
for(i=0; i<p->mxSample; i++){
if( p->a[i].isPSample ) continue;
if( (p->a[i].nSumEq<nMinEq)
|| (p->a[i].nSumEq==nMinEq && p->a[i].iHash<iHash)
){
iMin = i;
nMinEq = p->a[i].nSumEq;
iHash = p->a[i].iHash;
}
}
assert( iMin>=0 );
p->iMin = iMin;
}
}
static const FuncDef stat4PushFuncdef = {
-1, /* nArg */
SQLITE_UTF8, /* iPrefEnc */
0, /* flags */
0, /* pUserData */
0, /* pNext */
stat4Push, /* xFunc */
0, /* xStep */
0, /* xFinalize */
"stat4_push", /* zName */
0, /* pHash */
0 /* pDestructor */
};
/*
** Implementation of the stat3_get(P,N,...) SQL function. This routine is
** used to query the results. Content is returned for the Nth sqlite_stat3
** row where N is between 0 and S-1 and S is the number of samples. The
** value returned depends on the number of arguments.
**
** argc==2 result: rowid
** argc==3 result: nEq
** argc==4 result: nLt
** argc==5 result: nDLt
*/
static void stat4Get(
sqlite3_context *context,
int argc,
sqlite3_value **argv
){
Stat4Accum *p = (Stat4Accum*)sqlite3_value_blob(argv[0]);
int n = sqlite3_value_int(argv[1]);
assert( p!=0 );
if( n<p->nSample ){
tRowcnt *aCnt = 0;
char *zRet;
switch( argc ){
case 2:
sqlite3_result_int64(context, p->a[n].iRowid);
return;
case 3: aCnt = p->a[n].anEq; break;
case 4: aCnt = p->a[n].anLt; break;
default: aCnt = p->a[n].anDLt; break;
}
zRet = sqlite3MallocZero(p->nCol * 25);
if( zRet==0 ){
sqlite3_result_error_nomem(context);
}else{
int i;
char *z = zRet;
for(i=0; i<p->nCol; i++){
sqlite3_snprintf(24, z, "%lld ", aCnt[i]);
z += sqlite3Strlen30(z);
}
assert( z[0]=='\0' && z>zRet );
z[-1] = '\0';
sqlite3_result_text(context, zRet, -1, sqlite3_free);
}
}
}
static const FuncDef stat4GetFuncdef = {
-1, /* nArg */
SQLITE_UTF8, /* iPrefEnc */
0, /* flags */
0, /* pUserData */
0, /* pNext */
stat4Get, /* xFunc */
0, /* xStep */
0, /* xFinalize */
"stat4_get", /* zName */
0, /* pHash */
0 /* pDestructor */
};
#endif /* SQLITE_ENABLE_STAT4 */
/*
** Generate code to do an analysis of all indices associated with
** a single table.
*/
static void analyzeOneTable(
Parse *pParse, /* Parser context */
Table *pTab, /* Table whose indices are to be analyzed */
Index *pOnlyIdx, /* If not NULL, only analyze this one index */
int iStatCur, /* Index of VdbeCursor that writes the sqlite_stat1 table */
int iMem /* Available memory locations begin here */
){
sqlite3 *db = pParse->db; /* Database handle */
Index *pIdx; /* An index to being analyzed */
int iIdxCur; /* Cursor open on index being analyzed */
Vdbe *v; /* The virtual machine being built up */
int i; /* Loop counter */
int topOfLoop; /* The top of the loop */
int endOfLoop; /* The end of the loop */
int jZeroRows = -1; /* Jump from here if number of rows is zero */
int iDb; /* Index of database containing pTab */
u8 needTableCnt = 1; /* True to count the table */
int regTabname = iMem++; /* Register containing table name */
int regIdxname = iMem++; /* Register containing index name */
int regStat1 = iMem++; /* The stat column of sqlite_stat1 */
#ifdef SQLITE_ENABLE_STAT4
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 Stat4Accum object */
int regLoop = iMem++; /* Loop counter */
int regCount = iMem++; /* Number of rows in the table or index */
int regTemp1 = iMem++; /* Intermediate register */
int regTemp2 = iMem++; /* Intermediate register */
int once = 1; /* One-time initialization */
int shortJump = 0; /* Instruction address */
int iTabCur = pParse->nTab++; /* Table cursor */
#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 regNewRowid = iMem++; /* Rowid for the inserted record */
int regStat4 = iMem++; /* Register to hold Stat4Accum object */
v = sqlite3GetVdbe(pParse);
if( v==0 || NEVER(pTab==0) ){
return;
}
if( pTab->tnum==0 ){
/* Do not gather statistics on views or virtual tables */
return;
}
if( sqlite3_strnicmp(pTab->zName, "sqlite_", 7)==0 ){
/* Do not gather statistics on system tables */
return;
}
assert( sqlite3BtreeHoldsAllMutexes(db) );
iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
assert( iDb>=0 );
assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
#ifndef SQLITE_OMIT_AUTHORIZATION
if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,
db->aDb[iDb].zName ) ){
return;
}
#endif
/* Establish a read-lock on the table at the shared-cache level. */
sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
iIdxCur = pParse->nTab++;
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 */
KeyInfo *pKey; /* KeyInfo structure for pIdx */
int addrIfNot = 0; /* address of OP_IfNot */
int *aChngAddr; /* Array of jump instruction addresses */
int regRowid; /* Register for rowid of current row */
int regPrev; /* First in array of previous values */
int regDLt; /* First in array of nDlt registers */
int regLt; /* First in array of nLt registers */
int regEq; /* First in array of nEq registers */
int regCnt; /* Number of index entries */
int addrGoto;
if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
if( pIdx->pPartIdxWhere==0 ) needTableCnt = 0;
VdbeNoopComment((v, "Begin analysis of %s", pIdx->zName));
nCol = pIdx->nColumn;
aChngAddr = sqlite3DbMallocRaw(db, sizeof(int)*nCol);
if( aChngAddr==0 ) continue;
pKey = sqlite3IndexKeyinfo(pParse, pIdx);
/* Open a cursor to the index to be analyzed. */
assert( iDb==sqlite3SchemaToIndex(db, pIdx->pSchema) );
sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIdx->tnum, iDb,
(char *)pKey, P4_KEYINFO_HANDOFF);
VdbeComment((v, "%s", pIdx->zName));
/* Populate the register containing the index name. */
sqlite3VdbeAddOp4(v, OP_String8, 0, regIdxname, 0, pIdx->zName, 0);
#ifdef SQLITE_ENABLE_STAT4
if( once ){
once = 0;
sqlite3OpenTable(pParse, iTabCur, iDb, pTab, OP_OpenRead);
}
/* Invoke the stat4_init() function. The arguments are:
**
** * the number of rows in the index,
** * the number of columns in the index,
** * the recommended number of samples for the stat4 table.
*/
sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regStat4+1);
sqlite3VdbeAddOp2(v, OP_Integer, nCol, regStat4+2);
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_STAT4_SAMPLES, regStat4+3);
sqlite3VdbeAddOp3(v, OP_Function, 0, regStat4+1, regStat4);
sqlite3VdbeChangeP4(v, -1, (char*)&stat4InitFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 3);
#endif /* SQLITE_ENABLE_STAT4 */
/* The block of (1 + 4*nCol) memory cells initialized here is used
** as follows:
**
** TODO: Update this comment:
**
** iMem:
** Loop counter. The number of rows visited so far, including
** the current row (i.e. this register is set to 1 for the
** first iteration of the loop).
**
** iMem+1 .. iMem+nCol:
** Number of distinct index entries seen so far, considering
** the left-most N columns only, where N is between 1 and nCol,
** inclusive.
**
** iMem+nCol+1 .. Mem+2*nCol:
** Previous value of indexed columns, from left to right.
**
** Cells iMem through iMem+nCol are initialized to 0. The others are
** initialized to contain an SQL NULL.
*/
regRowid = regStat4+1; /* Rowid argument */
regEq = regRowid+1; /* First in array of nEq value registers */
regLt = regEq+nCol; /* First in array of nLt value registers */
regDLt = regLt+nCol; /* First in array of nDLt value registers */
regCnt = regDLt+nCol; /* Row counter */
regPrev = regCnt+1; /* First in array of prev. value registers */
if( regPrev+1>pParse->nMem ){
pParse->nMem = regPrev+1;
}
for(i=0; i<2+nCol*4; i++){
sqlite3VdbeAddOp2(v, OP_Integer, 0, regRowid+i);
}
/*
** Loop through all entries in the b-tree index. Pseudo-code for the
** body of the loop is as follows:
**
** foreach i IN index {
** regCnt += 1
**
** if( regEq(0)==0 ) goto ne_0;
**
** if i(0) != regPrev(0) {
** stat4_push(regRowid, regEq, regLt, regDLt);
** goto ne_0;
** }
** regEq(0) += 1
**
** if i(1) != regPrev(1){
** stat4_push(regRowid, regEq, regLt, regDLt);
** goto ne_1;
** }
** regEq(1) += 1
**
** goto all_eq;
**
** ne_0:
** regPrev(0) = i(0)
** if( regEq(0) != 0 ) regDLt(0) += 1
** regLt(0) += regEq(0)
** regEq(0) = 1
**
** ne_1:
** regPrev(1) = $i(1)
** if( regEq(1) != 0 ) regDLt(1) += 1
** regLt(1) += regEq(1)
** regEq(1) = 1
**
** all_eq:
** regRowid = i(rowid)
** }
**
** stat4_push(regRowid, regEq, regLt, regDLt);
**
** if( regEq(0) != 0 ) regDLt(0) += 1
** if( regEq(1) != 0 ) regDLt(1) += 1
**
** The last two lines above modify the contents of the regDLt array
** so that each element contains the number of distinct key prefixes
** of the corresponding length. As required to calculate the contents
** of the sqlite_stat1 entry.
**
** Note: if regEq(0)==0, stat4_push() is a no-op.
*/
endOfLoop = sqlite3VdbeMakeLabel(v);
sqlite3VdbeAddOp2(v, OP_Rewind, iIdxCur, endOfLoop);
topOfLoop = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_AddImm, regCnt, 1); /* Increment row counter */
/* This jump is taken for the first iteration of the loop only.
**
** if( regEq(0)==0 ) goto ne_0;
*/
addrIfNot = sqlite3VdbeAddOp1(v, OP_IfNot, regEq);
/* Code these bits:
**
** if i(N) != regPrev(N) {
** stat4_push(regRowid, regEq, regLt, regDLt);
** goto ne_N;
** }
** regEq(N) += 1
*/
for(i=0; i<nCol; i++){
char *pColl; /* Pointer to CollSeq cast to (char*) */
assert( pIdx->azColl && pIdx->azColl[i]!=0 );
pColl = (char*)sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regCol);
sqlite3VdbeAddOp4(v, OP_Eq, regCol, 0, regPrev+i, pColl, P4_COLLSEQ);
sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
sqlite3VdbeAddOp3(v, OP_Function, 1, regStat4, regTemp2);
sqlite3VdbeChangeP4(v, -1, (char*)&stat4PushFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 2 + 3*nCol);
aChngAddr[i] = sqlite3VdbeAddOp0(v, OP_Goto);
VdbeComment((v, "jump if column %d changed", i));
sqlite3VdbeJumpHere(v, sqlite3VdbeCurrentAddr(v)-3);
sqlite3VdbeAddOp2(v, OP_AddImm, regEq+i, 1);
VdbeComment((v, "incr repeat count"));
}
/* Code the "continue" */
addrGoto = sqlite3VdbeAddOp2(v, OP_Goto, 0, endOfLoop);
/* And now these:
**
** ne_N:
** regPrev(N) = i(N)
** if( regEq(N) != N ) regDLt(N) += 1
** regLt(N) += regEq(N)
** regEq(N) = 1
*/
for(i=0; i<nCol; i++){
sqlite3VdbeJumpHere(v, aChngAddr[i]); /* Set jump dest for the OP_Ne */
if( i==0 ){
sqlite3VdbeJumpHere(v, addrIfNot); /* Jump dest for OP_IfNot */
}
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regPrev+i);
sqlite3VdbeAddOp2(v, OP_IfNot, regEq+i, sqlite3VdbeCurrentAddr(v)+2);
sqlite3VdbeAddOp2(v, OP_AddImm, regDLt+i, 1);
sqlite3VdbeAddOp3(v, OP_Add, regEq+i, regLt+i, regLt+i);
sqlite3VdbeAddOp2(v, OP_Integer, 1, regEq+i);
}
sqlite3DbFree(db, aChngAddr);
/*
** all_eq:
** regRowid = i(rowid)
*/
sqlite3VdbeJumpHere(v, addrGoto);
sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, regRowid);
/* The end of the loop that iterates through all index entries. 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);
/* Final invocation of stat4_push() */
sqlite3VdbeAddOp3(v, OP_Function, 1, regStat4, regTemp2);
sqlite3VdbeChangeP4(v, -1, (char*)&stat4PushFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 2 + 3*nCol);
/* Finally:
**
** if( regEq(0) != 0 ) regDLt(0) += 1
*/
for(i=0; i<nCol; i++){
sqlite3VdbeAddOp2(v, OP_IfNot, regEq+i, sqlite3VdbeCurrentAddr(v)+2);
sqlite3VdbeAddOp2(v, OP_AddImm, regDLt+i, 1);
}
#ifdef SQLITE_ENABLE_STAT4
/* Add rows to the sqlite_stat4 table */
regLoop = regStat4+1;
sqlite3VdbeAddOp2(v, OP_Integer, -1, regLoop);
shortJump = sqlite3VdbeAddOp2(v, OP_AddImm, regLoop, 1);
sqlite3VdbeAddOp3(v, OP_Function, 0, regStat4, regTemp1);
sqlite3VdbeChangeP4(v, -1, (char*)&stat4GetFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 2);
sqlite3VdbeAddOp1(v, OP_IsNull, regTemp1);
sqlite3VdbeAddOp3(v, OP_NotExists, iTabCur, shortJump, regTemp1);
for(i=0; i<nCol; i++){
int iCol = pIdx->aiColumn[i];
sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur, iCol, regPrev+i);
}
sqlite3VdbeAddOp3(v, OP_MakeRecord, regPrev, nCol, regSample);
sqlite3VdbeChangeP4(v, -1, pIdx->zColAff, 0);
sqlite3VdbeAddOp3(v, OP_Function, 1, regStat4, regNumEq);
sqlite3VdbeChangeP4(v, -1, (char*)&stat4GetFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 3);
sqlite3VdbeAddOp3(v, OP_Function, 1, regStat4, regNumLt);
sqlite3VdbeChangeP4(v, -1, (char*)&stat4GetFuncdef, P4_FUNCDEF);
sqlite3VdbeChangeP5(v, 4);
sqlite3VdbeAddOp3(v, OP_Function, 1, regStat4, regNumDLt);
sqlite3VdbeChangeP4(v, -1, (char*)&stat4GetFuncdef, 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);
sqlite3VdbeJumpHere(v, shortJump+2);
#endif
/* Store the results in sqlite_stat1.
**
** The result is a single row of the sqlite_stat1 table. The first
** two columns are the names of the table and index. The third column
** is a string composed of a list of integer statistics about the
** index. The first integer in the list is the total number of entries
** in the index. There is one additional integer in the list for each
** column of the table. This additional integer is a guess of how many
** rows of the table the index will select. If D is the count of distinct
** values and K is the total number of rows, then the integer is computed
** as:
**
** I = (K+D-1)/D
**
** If K==0 then no entry is made into the sqlite_stat1 table.
** If K>0 then it is always the case the D>0 so division by zero
** is never possible.
*/
sqlite3VdbeAddOp2(v, OP_SCopy, regCnt, regStat1);
jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regCnt);
for(i=0; i<nCol; i++){
sqlite3VdbeAddOp4(v, OP_String8, 0, regTemp, 0, " ", 0);
sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regStat1, regStat1);
sqlite3VdbeAddOp3(v, OP_Add, regCnt, regDLt+i, regTemp);
sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
sqlite3VdbeAddOp3(v, OP_Divide, regDLt+i, regTemp, regTemp);
sqlite3VdbeAddOp1(v, OP_ToInt, regTemp);
sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regStat1, regStat1);
}
if( pIdx->pPartIdxWhere!=0 ) sqlite3VdbeJumpHere(v, jZeroRows);
sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regNewRowid);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
if( pIdx->pPartIdxWhere==0 ) sqlite3VdbeJumpHere(v, jZeroRows);
}
/* Create a single sqlite_stat1 entry containing NULL as the index
** name and the row count as the content.
*/
if( pOnlyIdx==0 && needTableCnt ){
sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pTab->tnum, iDb);
VdbeComment((v, "%s", pTab->zName));
sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regStat1);
sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regStat1);
sqlite3VdbeAddOp2(v, OP_Null, 0, regIdxname);
sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regNewRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regNewRowid);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
sqlite3VdbeJumpHere(v, jZeroRows);
}
if( pParse->nMem<regRec ) pParse->nMem = regRec;
}
/*
** Generate code that will cause the most recent index analysis to
** be loaded into internal hash tables where is can be used.
*/
static void loadAnalysis(Parse *pParse, int iDb){
Vdbe *v = sqlite3GetVdbe(pParse);
if( v ){
sqlite3VdbeAddOp1(v, OP_LoadAnalysis, iDb);
}
}
/*
** Generate code that will do an analysis of an entire database
*/
static void analyzeDatabase(Parse *pParse, int iDb){
sqlite3 *db = pParse->db;
Schema *pSchema = db->aDb[iDb].pSchema; /* Schema of database iDb */
HashElem *k;
int iStatCur;
int iMem;
sqlite3BeginWriteOperation(pParse, 0, iDb);
iStatCur = pParse->nTab;
pParse->nTab += 3;
openStatTable(pParse, iDb, iStatCur, 0, 0);
iMem = pParse->nMem+1;
assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){
Table *pTab = (Table*)sqliteHashData(k);
analyzeOneTable(pParse, pTab, 0, iStatCur, iMem);
}
loadAnalysis(pParse, iDb);
}
/*
** Generate code that will do an analysis of a single table in
** a database. If pOnlyIdx is not NULL then it is a single index
** in pTab that should be analyzed.
*/
static void analyzeTable(Parse *pParse, Table *pTab, Index *pOnlyIdx){
int iDb;
int iStatCur;
assert( pTab!=0 );
assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
sqlite3BeginWriteOperation(pParse, 0, iDb);
iStatCur = pParse->nTab;
pParse->nTab += 3;
if( pOnlyIdx ){
openStatTable(pParse, iDb, iStatCur, pOnlyIdx->zName, "idx");
}else{
openStatTable(pParse, iDb, iStatCur, pTab->zName, "tbl");
}
analyzeOneTable(pParse, pTab, pOnlyIdx, iStatCur, pParse->nMem+1);
loadAnalysis(pParse, iDb);
}
/*
** Generate code for the ANALYZE command. The parser calls this routine
** when it recognizes an ANALYZE command.
**
** ANALYZE -- 1
** ANALYZE <database> -- 2
** ANALYZE ?<database>.?<tablename> -- 3
**
** Form 1 causes all indices in all attached databases to be analyzed.
** Form 2 analyzes all indices the single database named.
** Form 3 analyzes all indices associated with the named table.
*/
void sqlite3Analyze(Parse *pParse, Token *pName1, Token *pName2){
sqlite3 *db = pParse->db;
int iDb;
int i;
char *z, *zDb;
Table *pTab;
Index *pIdx;
Token *pTableName;
/* Read the database schema. If an error occurs, leave an error message
** and code in pParse and return NULL. */
assert( sqlite3BtreeHoldsAllMutexes(pParse->db) );
if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
return;
}
assert( pName2!=0 || pName1==0 );
if( pName1==0 ){
/* Form 1: Analyze everything */
for(i=0; i<db->nDb; i++){
if( i==1 ) continue; /* Do not analyze the TEMP database */
analyzeDatabase(pParse, i);
}
}else if( pName2->n==0 ){
/* Form 2: Analyze the database or table named */
iDb = sqlite3FindDb(db, pName1);
if( iDb>=0 ){
analyzeDatabase(pParse, iDb);
}else{
z = sqlite3NameFromToken(db, pName1);
if( z ){
if( (pIdx = sqlite3FindIndex(db, z, 0))!=0 ){
analyzeTable(pParse, pIdx->pTable, pIdx);
}else if( (pTab = sqlite3LocateTable(pParse, 0, z, 0))!=0 ){
analyzeTable(pParse, pTab, 0);
}
sqlite3DbFree(db, z);
}
}
}else{
/* Form 3: Analyze the fully qualified table name */
iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pTableName);
if( iDb>=0 ){
zDb = db->aDb[iDb].zName;
z = sqlite3NameFromToken(db, pTableName);
if( z ){
if( (pIdx = sqlite3FindIndex(db, z, zDb))!=0 ){
analyzeTable(pParse, pIdx->pTable, pIdx);
}else if( (pTab = sqlite3LocateTable(pParse, 0, z, zDb))!=0 ){
analyzeTable(pParse, pTab, 0);
}
sqlite3DbFree(db, z);
}
}
}
}
/*
** Used to pass information from the analyzer reader through to the
** callback routine.
*/
typedef struct analysisInfo analysisInfo;
struct analysisInfo {
sqlite3 *db;
const char *zDatabase;
};
/*
** The first argument points to a nul-terminated string containing a
** list of space separated integers. Read the first nOut of these into
** the array aOut[].
*/
static void decodeIntArray(
char *zIntArray,
int nOut,
tRowcnt *aOut,
int *pbUnordered
){
char *z = zIntArray;
int c;
int i;
tRowcnt v;
assert( pbUnordered==0 || *pbUnordered==0 );
for(i=0; *z && i<nOut; i++){
v = 0;
while( (c=z[0])>='0' && c<='9' ){
v = v*10 + c - '0';
z++;
}
aOut[i] = v;
if( *z==' ' ) z++;
}
if( pbUnordered && strcmp(z, "unordered")==0 ){
*pbUnordered = 1;
}
}
/*
** This callback is invoked once for each index when reading the
** sqlite_stat1 table.
**
** argv[0] = name of the table
** argv[1] = name of the index (might be NULL)
** argv[2] = results of analysis - on integer for each column
**
** Entries for which argv[1]==NULL simply record the number of rows in
** the table.
*/
static int analysisLoader(void *pData, int argc, char **argv, char **NotUsed){
analysisInfo *pInfo = (analysisInfo*)pData;
Index *pIndex;
Table *pTable;
const char *z;
assert( argc==3 );
UNUSED_PARAMETER2(NotUsed, argc);
if( argv==0 || argv[0]==0 || argv[2]==0 ){
return 0;
}
pTable = sqlite3FindTable(pInfo->db, argv[0], pInfo->zDatabase);
if( pTable==0 ){
return 0;
}
if( argv[1] ){
pIndex = sqlite3FindIndex(pInfo->db, argv[1], pInfo->zDatabase);
}else{
pIndex = 0;
}
z = argv[2];
if( pIndex ){
int bUnordered = 0;
decodeIntArray((char*)z, pIndex->nColumn+1, pIndex->aiRowEst, &bUnordered);
if( pIndex->pPartIdxWhere==0 ) pTable->nRowEst = pIndex->aiRowEst[0];
pIndex->bUnordered = bUnordered;
}else{
decodeIntArray((char*)z, 1, &pTable->nRowEst, 0);
}
return 0;
}
/*
** If the Index.aSample variable is not NULL, delete the aSample[] array
** and its contents.
*/
void sqlite3DeleteIndexSamples(sqlite3 *db, Index *pIdx){
#ifdef SQLITE_ENABLE_STAT4
if( pIdx->aSample ){
int j;
for(j=0; j<pIdx->nSample; j++){
IndexSample *p = &pIdx->aSample[j];
sqlite3DbFree(db, p->p);
}
sqlite3DbFree(db, pIdx->aSample);
}
if( db && db->pnBytesFreed==0 ){
pIdx->nSample = 0;
pIdx->aSample = 0;
}
#else
UNUSED_PARAMETER(db);
UNUSED_PARAMETER(pIdx);
#endif
}
#ifdef SQLITE_ENABLE_STAT4
/*
** Load content from the sqlite_stat4 table into the Index.aSample[]
** arrays of all indices.
*/
static int loadStat4(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 = 0; /* slot in pIdx->aSample[] for next sample */
IndexSample *pSample; /* A slot in pIdx->aSample[] */
assert( db->lookaside.bEnabled==0 );
if( !sqlite3FindTable(db, "sqlite_stat4", zDb) ){
return SQLITE_OK;
}
zSql = sqlite3MPrintf(db,
"SELECT idx,count(*) FROM %Q.sqlite_stat4"
" 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 */
int nByte; /* Bytes of space required */
int i; /* Bytes of space required */
tRowcnt *pSpace;
zIndex = (char *)sqlite3_column_text(pStmt, 0);
if( zIndex==0 ) continue;
nSample = sqlite3_column_int(pStmt, 1);
pIdx = sqlite3FindIndex(db, zIndex, zDb);
if( pIdx==0 ) continue;
assert( pIdx->nSample==0 );
pIdx->nSample = nSample;
nByte = sizeof(IndexSample) * nSample;
nByte += sizeof(tRowcnt) * pIdx->nColumn * 3 * nSample;
pIdx->aSample = sqlite3DbMallocZero(db, nByte);
pIdx->avgEq = pIdx->aiRowEst[1];
if( pIdx->aSample==0 ){
sqlite3_finalize(pStmt);
return SQLITE_NOMEM;
}
pSpace = (tRowcnt*)&pIdx->aSample[nSample];
for(i=0; i<pIdx->nSample; i++){
pIdx->aSample[i].anEq = pSpace; pSpace += pIdx->nColumn;
pIdx->aSample[i].anLt = pSpace; pSpace += pIdx->nColumn;
pIdx->aSample[i].anDLt = pSpace; pSpace += pIdx->nColumn;
}
assert( ((u8*)pSpace)-nByte==(u8*)(pIdx->aSample) );
}
rc = sqlite3_finalize(pStmt);
if( rc ) return rc;
zSql = sqlite3MPrintf(db,
"SELECT idx,neq,nlt,ndlt,sample FROM %Q.sqlite_stat4", 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 i; /* Loop counter */
tRowcnt sumEq; /* Sum of the nEq values */
int nCol; /* Number of columns in index */
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];
nCol = pIdx->nColumn;
decodeIntArray((char*)sqlite3_column_text(pStmt,1), nCol, pSample->anEq, 0);
decodeIntArray((char*)sqlite3_column_text(pStmt,2), nCol, pSample->anLt, 0);
decodeIntArray((char*)sqlite3_column_text(pStmt,3), nCol, pSample->anDLt,0);
if( idx==pIdx->nSample-1 ){
if( pSample->anDLt[0]>0 ){
for(i=0, sumEq=0; i<=idx-1; i++) sumEq += pIdx->aSample[i].anEq[0];
pIdx->avgEq = (pSample->anLt[0] - sumEq)/pSample->anDLt[0];
}
if( pIdx->avgEq<=0 ) pIdx->avgEq = 1;
}
pSample->n = sqlite3_column_bytes(pStmt, 4);
pSample->p = sqlite3DbMallocZero(db, pSample->n);
if( pSample->p==0 ){
sqlite3_finalize(pStmt);
return SQLITE_NOMEM;
}
memcpy(pSample->p, sqlite3_column_blob(pStmt, 4), pSample->n);
}
return sqlite3_finalize(pStmt);
}
#endif /* SQLITE_ENABLE_STAT4 */
/*
** Load the content of the sqlite_stat1 and sqlite_stat4 tables. The
** contents of sqlite_stat1 are used to populate the Index.aiRowEst[]
** arrays. The contents of sqlite_stat4 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_STAT4 was defined
** during compilation and the sqlite_stat4 table is present, no data is
** read from it.
**
** If SQLITE_ENABLE_STAT4 was defined during compilation and the
** sqlite_stat4 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.
**
** If an OOM error occurs, this function always sets db->mallocFailed.
** This means if the caller does not care about other errors, the return
** code may be ignored.
*/
int sqlite3AnalysisLoad(sqlite3 *db, int iDb){
analysisInfo sInfo;
HashElem *i;
char *zSql;
int rc;
assert( iDb>=0 && iDb<db->nDb );
assert( db->aDb[iDb].pBt!=0 );
/* Clear any prior statistics */
assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){
Index *pIdx = sqliteHashData(i);
sqlite3DefaultRowEst(pIdx);
#ifdef SQLITE_ENABLE_STAT4
sqlite3DeleteIndexSamples(db, pIdx);
pIdx->aSample = 0;
#endif
}
/* Check to make sure the sqlite_stat1 table exists */
sInfo.db = db;
sInfo.zDatabase = db->aDb[iDb].zName;
if( sqlite3FindTable(db, "sqlite_stat1", sInfo.zDatabase)==0 ){
return SQLITE_ERROR;
}
/* Load new statistics out of the sqlite_stat1 table */
zSql = sqlite3MPrintf(db,
"SELECT tbl,idx,stat FROM %Q.sqlite_stat1", sInfo.zDatabase);
if( zSql==0 ){
rc = SQLITE_NOMEM;
}else{
rc = sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0);
sqlite3DbFree(db, zSql);
}
/* Load the statistics from the sqlite_stat4 table. */
#ifdef SQLITE_ENABLE_STAT4
if( rc==SQLITE_OK ){
int lookasideEnabled = db->lookaside.bEnabled;
db->lookaside.bEnabled = 0;
rc = loadStat4(db, sInfo.zDatabase);
db->lookaside.bEnabled = lookasideEnabled;
}
#endif
if( rc==SQLITE_NOMEM ){
db->mallocFailed = 1;
}
return rc;
}
#endif /* SQLITE_OMIT_ANALYZE */