/*
** 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.
**
** @(#) $Id: analyze.c,v 1.2 2005/07/23 00:41:49 drh Exp $
*/
#ifndef SQLITE_OMIT_ANALYZE
#include "sqliteInt.h"
/*
** This routine generates code that opens the sqlite_stat1 table on cursor
** iStatCur.
**
** If the sqlite_stat1 tables does not previously exist, it is created.
** If it does previously exist, all entires associated with table zWhere
** are removed. If zWhere==0 then all entries are removed.
*/
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 associated with this table */
){
sqlite3 *db = pParse->db;
Db *pDb;
int iRootPage;
Table *pStat;
Vdbe *v = sqlite3GetVdbe(pParse);
pDb = &db->aDb[iDb];
if( (pStat = sqlite3FindTable(db, "sqlite_stat1", pDb->zName))==0 ){
/* The sqlite_stat1 tables does not exist. Create it.
** Note that a side-effect of the CREATE TABLE statement is to leave
** the rootpage of the new table on the top of the stack. This is
** important because the OpenWrite opcode below will be needing it. */
sqlite3NestedParse(pParse,
"CREATE TABLE %Q.sqlite_stat1(tbl,idx,stat)",
pDb->zName
);
iRootPage = 0; /* Cause rootpage to be taken from top of stack */
}else if( zWhere ){
/* The sqlite_stat1 table exists. Delete all entries associated with
** the table zWhere. */
sqlite3NestedParse(pParse,
"DELETE FROM %Q.sqlite_stat1 WHERE tbl=%Q",
pDb->zName, zWhere
);
iRootPage = pStat->tnum;
}else{
/* The sqlite_stat1 table already exists. Delete all rows. */
iRootPage = pStat->tnum;
sqlite3VdbeAddOp(v, OP_Clear, pStat->tnum, iDb);
}
/* Open the sqlite_stat1 table for writing.
*/
sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
sqlite3VdbeAddOp(v, OP_OpenWrite, iStatCur, 0);
sqlite3VdbeAddOp(v, OP_SetNumColumns, iStatCur, 3);
}
/*
** 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 */
int iStatCur, /* Cursor that writes to the sqlite_stat1 table */
int iMem /* Available memory locations begin here */
){
Index *pIdx; /* An index to being analyzed */
int iIdxCur; /* Cursor number for index being analyzed */
int nCol; /* Number of columns in the index */
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 addr; /* The address of an instruction */
v = sqlite3GetVdbe(pParse);
if( pTab==0 || pTab->pIndex==0 || pTab->pIndex->pNext==0 ){
/* Do no analysis for tables with fewer than 2 indices */
return;
}
iIdxCur = pParse->nTab;
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
/* Open a cursor to the index to be analyzed
*/
sqlite3VdbeAddOp(v, OP_Integer, pIdx->iDb, 0);
VdbeComment((v, "# %s", pIdx->zName));
sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIdx->tnum,
(char*)&pIdx->keyInfo, P3_KEYINFO);
nCol = pIdx->nColumn;
if( iMem+nCol*2>=pParse->nMem ){
pParse->nMem = iMem+nCol*2+1;
}
sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, nCol+1);
/* Memory cells are used as follows:
**
** mem[iMem]: The total number of rows in the table.
** mem[iMem+1]: Number of distinct values in column 1
** ...
** mem[iMem+nCol]: Number of distinct values in column N
** mem[iMem+nCol+1] Last observed value of column 1
** ...
** mem[iMem+nCol+nCol]: Last observed value of column N
**
** Cells iMem through iMem+nCol are initialized to 0. The others
** are initialized to NULL.
*/
sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
for(i=0; i<=nCol; i++){
sqlite3VdbeAddOp(v, OP_MemStore, iMem+i, i==nCol);
}
sqlite3VdbeAddOp(v, OP_Null, 0, 0);
for(i=0; i<nCol; i++){
sqlite3VdbeAddOp(v, OP_MemStore, iMem+nCol+i+1, i==nCol-1);
}
/* Do the analysis.
*/
sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, 0);
topOfLoop = sqlite3VdbeCurrentAddr(v);
endOfLoop = sqlite3VdbeMakeLabel(v);
sqlite3VdbeAddOp(v, OP_MemIncr, iMem, 0);
for(i=0; i<nCol; i++){
sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
sqlite3VdbeAddOp(v, OP_MemLoad, iMem+nCol+i+1, 0);
sqlite3VdbeAddOp(v, OP_Ne, 0x100, 0);
}
sqlite3VdbeAddOp(v, OP_Goto, 0, endOfLoop);
for(i=0; i<nCol; i++){
addr = sqlite3VdbeAddOp(v, OP_MemIncr, iMem+i+1, 0);
sqlite3VdbeChangeP2(v, topOfLoop + 3*i + 3, addr);
sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
sqlite3VdbeAddOp(v, OP_MemStore, iMem+nCol+i+1, 1);
}
sqlite3VdbeResolveLabel(v, endOfLoop);
sqlite3VdbeAddOp(v, OP_Next, iIdxCur, topOfLoop);
sqlite3VdbeAddOp(v, OP_Close, iIdxCur, 0);
/* Store the results.
**
** The result is a single row of the sqlite_stmt1 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. There is one integer in the list for each column of the table.
** This 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.
*/
sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
addr = sqlite3VdbeAddOp(v, OP_IfNot, 0, 0);
sqlite3VdbeAddOp(v, OP_NewRowid, iStatCur, 0);
sqlite3VdbeOp3(v, OP_String8, 0, 0, pTab->zName, 0);
sqlite3VdbeOp3(v, OP_String8, 0, 0, pIdx->zName, 0);
for(i=0; i<nCol; i++){
sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
sqlite3VdbeAddOp(v, OP_MemLoad, iMem+i+1, 0);
sqlite3VdbeAddOp(v, OP_Add, 0, 0);
sqlite3VdbeAddOp(v, OP_AddImm, -1, 0);
sqlite3VdbeAddOp(v, OP_MemLoad, iMem+i+1, 0);
sqlite3VdbeAddOp(v, OP_Divide, 0, 0);
if( i==nCol-1 ){
if( i>0 ){
sqlite3VdbeAddOp(v, OP_Concat, nCol*2-3, 0);
}
}else{
if( i==0 ){
sqlite3VdbeOp3(v, OP_String8, 0, 0, " ", 0);
}else{
sqlite3VdbeAddOp(v, OP_Dup, 1, 0);
}
}
}
sqlite3VdbeOp3(v, OP_MakeRecord, 3, 0, "ttt", 0);
sqlite3VdbeAddOp(v, OP_Insert, iStatCur, 0);
sqlite3VdbeChangeP2(v, addr, sqlite3VdbeCurrentAddr(v));
}
}
/*
** Generate code that will do an analysis of an entire database
*/
static void analyzeDatabase(Parse *pParse, int iDb){
sqlite3 *db = pParse->db;
HashElem *k;
int iStatCur;
int iMem;
sqlite3BeginWriteOperation(pParse, 0, iDb);
iStatCur = pParse->nTab++;
openStatTable(pParse, iDb, iStatCur, 0);
iMem = pParse->nMem;
for(k=sqliteHashFirst(&db->aDb[iDb].tblHash); k; k=sqliteHashNext(k)){
Table *pTab = (Table*)sqliteHashData(k);
analyzeOneTable(pParse, pTab, iStatCur, iMem);
}
}
/*
** Generate code that will do an analysis of a single table in
** a database.
*/
static void analyzeTable(Parse *pParse, Table *pTab){
int iDb;
int iStatCur;
assert( pTab!=0 );
iDb = pTab->iDb;
sqlite3BeginWriteOperation(pParse, 0, iDb);
iStatCur = pParse->nTab++;
openStatTable(pParse, iDb, iStatCur, pTab->zName);
analyzeOneTable(pParse, pTab, iStatCur, pParse->nMem);
}
/*
** 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;
Token *pTableName;
/* Read the database schema. If an error occurs, leave an error message
** and code in pParse and return NULL. */
if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
return;
}
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==0 ){
/* Form 2: Analyze the database or table named */
iDb = sqlite3FindDb(db, pName1);
if( iDb>=0 ){
analyzeDatabase(pParse, iDb);
return;
}
z = sqlite3NameFromToken(pName1);
pTab = sqlite3LocateTable(pParse, z, 0);
sqliteFree(z);
if( pTab ){
analyzeTable(pParse, pTab);
}
return;
}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(pTableName);
pTab = sqlite3LocateTable(pParse, z, zDb);
sqliteFree(z);
if( pTab ){
analyzeTable(pParse, pTab);
}
}
}
}
#endif /* SQLITE_OMIT_ANALYZE */