/*** 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 1.16 2006/01/10 17:58:23 danielk1977 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. Unless it was created  ** by this vdbe program, lock it for writing at the shared-cache level.   ** If this vdbe did create the sqlite_stat1 table, then it must have   ** already obtained a schema-lock, making the write-lock redundant.  */  if( iRootPage>0 ){    sqlite3TableLock(pParse, iDb, iRootPage, 1, "sqlite_stat1");  }  sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);  sqlite3VdbeAddOp(v, OP_OpenWrite, iStatCur, iRootPage);  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 */  int iDb;         /* Index of database containing pTab */  v = sqlite3GetVdbe(pParse);  if( pTab==0 || pTab->pIndex==0 ){    /* Do no analysis for tables that have no indices */    return;  }  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);  assert( iDb>=0 );#ifndef SQLITE_OMIT_AUTHORIZATION  if( sqlite3AuthCheck(pParse, SQLITE_ANALYZE, pTab->zName, 0,      pParse->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;  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){    KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIdx);    /* Open a cursor to the index to be analyzed    */    assert( iDb==sqlite3SchemaToIndex(pParse->db, pIdx->pSchema) );    sqlite3VdbeAddOp(v, OP_Integer, iDb, 0);    VdbeComment((v, "# %s", pIdx->zName));    sqlite3VdbeOp3(v, OP_OpenRead, iIdxCur, pIdx->tnum,        (char *)pKey, P3_KEYINFO_HANDOFF);    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.    */    for(i=0; i<=nCol; i++){      sqlite3VdbeAddOp(v, OP_MemInt, 0, iMem+i);    }    for(i=0; i<nCol; i++){      sqlite3VdbeAddOp(v, OP_MemNull, iMem+nCol+i+1, 0);    }    /* Do the analysis.    */    endOfLoop = sqlite3VdbeMakeLabel(v);    sqlite3VdbeAddOp(v, OP_Rewind, iIdxCur, endOfLoop);    topOfLoop = sqlite3VdbeCurrentAddr(v);    sqlite3VdbeAddOp(v, OP_MemIncr, 1, iMem);    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, 1, iMem+i+1);      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.  The first integer in the list is the total number of entires    ** 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.    */    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);    sqlite3VdbeAddOp(v, OP_MemLoad, iMem, 0);    sqlite3VdbeOp3(v, OP_String8, 0, 0, " ", 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);      sqlite3VdbeAddOp(v, OP_ToInt, 0, 0);      if( i==nCol-1 ){        sqlite3VdbeAddOp(v, OP_Concat, nCol*2-1, 0);      }else{        sqlite3VdbeAddOp(v, OP_Dup, 1, 0);      }    }    sqlite3VdbeOp3(v, OP_MakeRecord, 3, 0, "aaa", 0);    sqlite3VdbeAddOp(v, OP_Insert, iStatCur, 0);    sqlite3VdbeJumpHere(v, addr);  }}/*** Generate code that will cause the most recent index analysis to** be laoded into internal hash tables where is can be used.*/static void loadAnalysis(Parse *pParse, int iDb){  Vdbe *v = sqlite3GetVdbe(pParse);  sqlite3VdbeAddOp(v, OP_LoadAnalysis, iDb, 0);}/*** 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++;  openStatTable(pParse, iDb, iStatCur, 0);  iMem = pParse->nMem;  for(k=sqliteHashFirst(&pSchema->tblHash); k; k=sqliteHashNext(k)){    Table *pTab = (Table*)sqliteHashData(k);    analyzeOneTable(pParse, pTab, iStatCur, iMem);  }  loadAnalysis(pParse, iDb);}/*** 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 = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);  sqlite3BeginWriteOperation(pParse, 0, iDb);  iStatCur = pParse->nTab++;  openStatTable(pParse, iDb, iStatCur, pTab->zName);  analyzeOneTable(pParse, pTab, iStatCur, pParse->nMem);  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;  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 || pName2->n==0 ){    /* Form 2:  Analyze the database or table named */    iDb = sqlite3FindDb(db, pName1);    if( iDb>=0 ){      analyzeDatabase(pParse, iDb);    }else{      z = sqlite3NameFromToken(pName1);      pTab = sqlite3LocateTable(pParse, z, 0);      sqliteFree(z);      if( pTab ){        analyzeTable(pParse, pTab);      }    }  }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);      }    }     }}/*** Used to pass information from the analyzer reader through to the** callback routine.*/typedef struct analysisInfo analysisInfo;struct analysisInfo {  sqlite3 *db;  const char *zDatabase;};/*** This callback is invoked once for each index when reading the** sqlite_stat1 table.  ****     argv[0] = name of the index**     argv[1] = results of analysis - on integer for each column*/static int analysisLoader(void *pData, int argc, char **argv, char **azNotUsed){  analysisInfo *pInfo = (analysisInfo*)pData;  Index *pIndex;  int i, c;  unsigned int v;  const char *z;  assert( argc==2 );  if( argv==0 || argv[0]==0 || argv[1]==0 ){    return 0;  }  pIndex = sqlite3FindIndex(pInfo->db, argv[0], pInfo->zDatabase);  if( pIndex==0 ){    return 0;  }  z = argv[1];  for(i=0; *z && i<=pIndex->nColumn; i++){    v = 0;    while( (c=z[0])>='0' && c<='9' ){      v = v*10 + c - '0';      z++;    }    pIndex->aiRowEst[i] = v;    if( *z==' ' ) z++;  }  return 0;}/*** Load the content of the sqlite_stat1 table into the index hash tables.*/void sqlite3AnalysisLoad(sqlite3 *db, int iDb){  analysisInfo sInfo;  HashElem *i;  char *zSql;  /* Clear any prior statistics */  for(i=sqliteHashFirst(&db->aDb[iDb].pSchema->idxHash);i;i=sqliteHashNext(i)){    Index *pIdx = sqliteHashData(i);    sqlite3DefaultRowEst(pIdx);  }  /* Check to make sure the sqlite_stat1 table existss */  sInfo.db = db;  sInfo.zDatabase = db->aDb[iDb].zName;  if( sqlite3FindTable(db, "sqlite_stat1", sInfo.zDatabase)==0 ){     return;  }  /* Load new statistics out of the sqlite_stat1 table */  zSql = sqlite3MPrintf("SELECT idx, stat FROM %Q.sqlite_stat1",                        sInfo.zDatabase);  sqlite3SafetyOff(db);  sqlite3_exec(db, zSql, analysisLoader, &sInfo, 0);  sqlite3SafetyOn(db);  sqliteFree(zSql);}#endif /* SQLITE_OMIT_ANALYZE */