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387 lines
12 KiB
387 lines
12 KiB
/*
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** 2005 July 8
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**
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** The author disclaims copyright to this source code. In place of
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** a legal notice, here is a blessing:
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**
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** May you do good and not evil.
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** May you find forgiveness for yourself and forgive others.
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** May you share freely, never taking more than you give.
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**
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*************************************************************************
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** This file contains code associated with the ANALYZE command.
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**
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** @(#) $Id: analyze.c,v 1.9 2005/09/20 17:42:23 drh Exp $
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*/
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#ifndef SQLITE_OMIT_ANALYZE
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#include "sqliteInt.h"
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/*
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** This routine generates code that opens the sqlite_stat1 table on cursor
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** iStatCur.
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**
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** If the sqlite_stat1 tables does not previously exist, it is created.
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** If it does previously exist, all entires associated with table zWhere
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** are removed. If zWhere==0 then all entries are removed.
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*/
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static void openStatTable(
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Parse *pParse, /* Parsing context */
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int iDb, /* The database we are looking in */
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int iStatCur, /* Open the sqlite_stat1 table on this cursor */
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const char *zWhere /* Delete entries associated with this table */
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){
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sqlite3 *db = pParse->db;
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Db *pDb;
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int iRootPage;
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Table *pStat;
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Vdbe *v = sqlite3GetVdbe(pParse);
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pDb = &db->aDb[iDb];
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if( (pStat = sqlite3FindTable(db, "sqlite_stat1", pDb->zName))==0 ){
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/* The sqlite_stat1 tables does not exist. Create it.
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** Note that a side-effect of the CREATE TABLE statement is to leave
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** the rootpage of the new table on the top of the stack. This is
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** important because the OpenWrite opcode below will be needing it. */
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sqlite3NestedParse(pParse,
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"CREATE TABLE %Q.sqlite_stat1(tbl,idx,stat)",
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pDb->zName
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);
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iRootPage = 0; /* Cause rootpage to be taken from top of stack */
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}else if( zWhere ){
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/* The sqlite_stat1 table exists. Delete all entries associated with
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** the table zWhere. */
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sqlite3NestedParse(pParse,
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"DELETE FROM %Q.sqlite_stat1 WHERE tbl=%Q",
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pDb->zName, zWhere
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);
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iRootPage = pStat->tnum;
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}else{
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/* The sqlite_stat1 table already exists. Delete all rows. */
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iRootPage = pStat->tnum;
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sqlite3VdbeAddOp(v, OP_Clear, pStat->tnum, iDb);
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}
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/* Open the sqlite_stat1 table for writing.
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*/
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sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);
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sqlite3VdbeAddOp(v, OP_OpenWrite, iStatCur, iRootPage);
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sqlite3VdbeAddOp(v, OP_SetNumColumns, iStatCur, 3);
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}
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/*
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** Generate code to do an analysis of all indices associated with
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** a single table.
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*/
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static void analyzeOneTable(
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Parse *pParse, /* Parser context */
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Table *pTab, /* Table whose indices are to be analyzed */
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int iStatCur, /* Cursor that writes to the sqlite_stat1 table */
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int iMem /* Available memory locations begin here */
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){
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Index *pIdx; /* An index to being analyzed */
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int iIdxCur; /* Cursor number for index being analyzed */
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int nCol; /* Number of columns in the index */
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Vdbe *v; /* The virtual machine being built up */
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int i; /* Loop counter */
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int topOfLoop; /* The top of the loop */
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int endOfLoop; /* The end of the loop */
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int addr; /* The address of an instruction */
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v = sqlite3GetVdbe(pParse);
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if( pTab==0 || pTab->pIndex==0 ){
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/* Do no analysis for tables that have no indices */
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return;
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}
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#ifndef SQLITE_OMIT_AUTHORIZATION
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if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,
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pParse->db->aDb[pTab->iDb].zName ) ){
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return;
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}
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#endif
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iIdxCur = pParse->nTab;
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for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
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/* Open a cursor to the index to be analyzed
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*/
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sqlite3VdbeAddOp(v, OP_Integer, pIdx->iDb, 0);
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VdbeComment((v, "# %s", pIdx->zName));
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sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIdx->tnum,
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(char*)&pIdx->keyInfo, P3_KEYINFO);
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nCol = pIdx->nColumn;
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if( iMem+nCol*2>=pParse->nMem ){
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pParse->nMem = iMem+nCol*2+1;
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}
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sqlite3VdbeAddOp(v, OP_SetNumColumns, iIdxCur, nCol+1);
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/* Memory cells are used as follows:
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**
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** mem[iMem]: The total number of rows in the table.
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** mem[iMem+1]: Number of distinct values in column 1
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** ...
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** mem[iMem+nCol]: Number of distinct values in column N
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** mem[iMem+nCol+1] Last observed value of column 1
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** ...
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** mem[iMem+nCol+nCol]: Last observed value of column N
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**
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** Cells iMem through iMem+nCol are initialized to 0. The others
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** are initialized to NULL.
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*/
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for(i=0; i<=nCol; i++){
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sqlite3VdbeAddOp(v, OP_MemInt, 0, iMem+i);
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}
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for(i=0; i<nCol; i++){
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sqlite3VdbeAddOp(v, OP_MemNull, iMem+nCol+i+1, 0);
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}
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/* Do the analysis.
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*/
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endOfLoop = sqlite3VdbeMakeLabel(v);
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sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, endOfLoop);
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topOfLoop = sqlite3VdbeCurrentAddr(v);
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sqlite3VdbeAddOp(v, OP_MemIncr, iMem, 0);
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for(i=0; i<nCol; i++){
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sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
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sqlite3VdbeAddOp(v, OP_MemLoad, iMem+nCol+i+1, 0);
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sqlite3VdbeAddOp(v, OP_Ne, 0x100, 0);
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}
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sqlite3VdbeAddOp(v, OP_Goto, 0, endOfLoop);
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for(i=0; i<nCol; i++){
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addr = sqlite3VdbeAddOp(v, OP_MemIncr, iMem+i+1, 0);
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sqlite3VdbeChangeP2(v, topOfLoop + 3*i + 3, addr);
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sqlite3VdbeAddOp(v, OP_Column, iIdxCur, i);
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sqlite3VdbeAddOp(v, OP_MemStore, iMem+nCol+i+1, 1);
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}
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sqlite3VdbeResolveLabel(v, endOfLoop);
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sqlite3VdbeAddOp(v, OP_Next, iIdxCur, topOfLoop);
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sqlite3VdbeAddOp(v, OP_Close, iIdxCur, 0);
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/* Store the results.
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**
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** The result is a single row of the sqlite_stmt1 table. The first
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** two columns are the names of the table and index. The third column
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** is a string composed of a list of integer statistics about the
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** index. The first integer in the list is the total number of entires
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** in the index. There is one additional integer in the list for each
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** column of the table. This additional integer is a guess of how many
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** rows of the table the index will select. If D is the count of distinct
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** values and K is the total number of rows, then the integer is computed
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** as:
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**
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** I = (K+D-1)/D
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**
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** If K==0 then no entry is made into the sqlite_stat1 table.
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** If K>0 then it is always the case the D>0 so division by zero
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** is never possible.
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*/
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sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
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addr = sqlite3VdbeAddOp(v, OP_IfNot, 0, 0);
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sqlite3VdbeAddOp(v, OP_NewRowid, iStatCur, 0);
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sqlite3VdbeOp3(v, OP_String8, 0, 0, pTab->zName, 0);
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sqlite3VdbeOp3(v, OP_String8, 0, 0, pIdx->zName, 0);
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sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
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sqlite3VdbeOp3(v, OP_String8, 0, 0, " ", 0);
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for(i=0; i<nCol; i++){
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sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);
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sqlite3VdbeAddOp(v, OP_MemLoad, iMem+i+1, 0);
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sqlite3VdbeAddOp(v, OP_Add, 0, 0);
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sqlite3VdbeAddOp(v, OP_AddImm, -1, 0);
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sqlite3VdbeAddOp(v, OP_MemLoad, iMem+i+1, 0);
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sqlite3VdbeAddOp(v, OP_Divide, 0, 0);
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if( i==nCol-1 ){
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sqlite3VdbeAddOp(v, OP_Concat, nCol*2-1, 0);
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}else{
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sqlite3VdbeAddOp(v, OP_Dup, 1, 0);
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}
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}
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sqlite3VdbeOp3(v, OP_MakeRecord, 3, 0, "ttt", 0);
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sqlite3VdbeAddOp(v, OP_Insert, iStatCur, 0);
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sqlite3VdbeJumpHere(v, addr);
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}
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}
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/*
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** Generate code that will cause the most recent index analysis to
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** be laoded into internal hash tables where is can be used.
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*/
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static void loadAnalysis(Parse *pParse, int iDb){
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Vdbe *v = sqlite3GetVdbe(pParse);
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sqlite3VdbeAddOp(v, OP_LoadAnalysis, iDb, 0);
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}
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/*
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** Generate code that will do an analysis of an entire database
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*/
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static void analyzeDatabase(Parse *pParse, int iDb){
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sqlite3 *db = pParse->db;
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HashElem *k;
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int iStatCur;
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int iMem;
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sqlite3BeginWriteOperation(pParse, 0, iDb);
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iStatCur = pParse->nTab++;
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openStatTable(pParse, iDb, iStatCur, 0);
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iMem = pParse->nMem;
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for(k=sqliteHashFirst(&db->aDb[iDb].tblHash); k; k=sqliteHashNext(k)){
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Table *pTab = (Table*)sqliteHashData(k);
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analyzeOneTable(pParse, pTab, iStatCur, iMem);
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}
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loadAnalysis(pParse, iDb);
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}
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/*
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** Generate code that will do an analysis of a single table in
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** a database.
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*/
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static void analyzeTable(Parse *pParse, Table *pTab){
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int iDb;
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int iStatCur;
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assert( pTab!=0 );
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iDb = pTab->iDb;
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sqlite3BeginWriteOperation(pParse, 0, iDb);
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iStatCur = pParse->nTab++;
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openStatTable(pParse, iDb, iStatCur, pTab->zName);
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analyzeOneTable(pParse, pTab, iStatCur, pParse->nMem);
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loadAnalysis(pParse, iDb);
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}
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/*
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** Generate code for the ANALYZE command. The parser calls this routine
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** when it recognizes an ANALYZE command.
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**
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** ANALYZE -- 1
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** ANALYZE <database> -- 2
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** ANALYZE ?<database>.?<tablename> -- 3
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**
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** Form 1 causes all indices in all attached databases to be analyzed.
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** Form 2 analyzes all indices the single database named.
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** Form 3 analyzes all indices associated with the named table.
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*/
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void sqlite3Analyze(Parse *pParse, Token *pName1, Token *pName2){
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sqlite3 *db = pParse->db;
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int iDb;
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int i;
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char *z, *zDb;
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Table *pTab;
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Token *pTableName;
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/* Read the database schema. If an error occurs, leave an error message
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** and code in pParse and return NULL. */
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if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){
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return;
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}
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if( pName1==0 ){
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/* Form 1: Analyze everything */
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for(i=0; i<db->nDb; i++){
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if( i==1 ) continue; /* Do not analyze the TEMP database */
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analyzeDatabase(pParse, i);
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}
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}else if( pName2==0 || pName2->n==0 ){
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/* Form 2: Analyze the database or table named */
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iDb = sqlite3FindDb(db, pName1);
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if( iDb>=0 ){
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analyzeDatabase(pParse, iDb);
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}else{
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z = sqlite3NameFromToken(pName1);
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pTab = sqlite3LocateTable(pParse, z, 0);
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sqliteFree(z);
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if( pTab ){
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analyzeTable(pParse, pTab);
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}
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}
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}else{
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/* Form 3: Analyze the fully qualified table name */
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iDb = sqlite3TwoPartName(pParse, pName1, pName2, &pTableName);
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if( iDb>=0 ){
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zDb = db->aDb[iDb].zName;
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z = sqlite3NameFromToken(pTableName);
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pTab = sqlite3LocateTable(pParse, z, zDb);
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sqliteFree(z);
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if( pTab ){
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analyzeTable(pParse, pTab);
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}
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}
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}
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}
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/*
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** Used to pass information from the analyzer reader through to the
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** callback routine.
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*/
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typedef struct analysisInfo analysisInfo;
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struct analysisInfo {
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sqlite3 *db;
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const char *zDatabase;
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};
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/*
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** This callback is invoked once for each index when reading the
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** sqlite_stat1 table.
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**
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** argv[0] = name of the index
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** argv[1] = results of analysis - on integer for each column
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*/
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static int analysisLoader(void *pData, int argc, char **argv, char **azNotUsed){
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analysisInfo *pInfo = (analysisInfo*)pData;
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Index *pIndex;
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int i, c;
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unsigned int v;
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const char *z;
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assert( argc==2 );
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if( argv==0 || argv[0]==0 || argv[1]==0 ){
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return 0;
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}
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pIndex = sqlite3FindIndex(pInfo->db, argv[0], pInfo->zDatabase);
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if( pIndex==0 ){
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return 0;
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}
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z = argv[1];
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for(i=0; *z && i<=pIndex->nColumn; i++){
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v = 0;
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while( (c=z[0])>='0' && c<='9' ){
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v = v*10 + c - '0';
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z++;
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}
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pIndex->aiRowEst[i] = v;
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if( *z==' ' ) z++;
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}
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return 0;
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}
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/*
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** Load the content of the sqlite_stat1 table into the index hash tables.
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*/
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void sqlite3AnalysisLoad(sqlite3 *db, int iDb){
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analysisInfo sInfo;
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HashElem *i;
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char *zSql;
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/* Clear any prior statistics */
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for(i=sqliteHashFirst(&db->aDb[iDb].idxHash); i; i=sqliteHashNext(i)){
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Index *pIdx = sqliteHashData(i);
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sqlite3DefaultRowEst(pIdx);
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}
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/* Check to make sure the sqlite_stat1 table existss */
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sInfo.db = db;
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sInfo.zDatabase = db->aDb[iDb].zName;
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if( sqlite3FindTable(db, "sqlite_stat1", sInfo.zDatabase)==0 ){
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return;
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}
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/* Load new statistics out of the sqlite_stat1 table */
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zSql = sqlite3MPrintf("SELECT idx, stat FROM %Q.sqlite_stat1",
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sInfo.zDatabase);
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sqlite3SafetyOff(db);
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sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0);
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sqlite3SafetyOn(db);
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sqliteFree(zSql);
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}
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#endif /* SQLITE_OMIT_ANALYZE */
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