/* ** 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 ** The sqlite_stat2 table is superceded by sqlite_stat3, which is only ** created and used by SQLite versions 3.7.9 and later and with ** SQLITE_ENABLE_STAT3 defined.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_STAT3 macro defined, then the sqlite_stat3 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_stat3 table does not exist and the library ** is compiled with SQLITE_ENABLE_STAT3 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_stat3 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_STAT3 { "sqlite_stat3", "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; izName))==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] = 1; }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[13] tables for writing. */ for(i=0; ia[0])*mxSample; p = sqlite3_malloc( n ); if( p==0 ){ sqlite3_result_error_nomem(context); return; } memset(p, 0, n); p->a = (struct Stat3Sample*)&p[1]; p->nRow = nRow; p->mxSample = mxSample; p->nPSample = p->nRow/(mxSample/3+1) + 1; sqlite3_randomness(sizeof(p->iPrn), &p->iPrn); sqlite3_result_blob(context, p, sizeof(p), sqlite3_free); } static const FuncDef stat3InitFuncdef = { 2, /* nArg */ SQLITE_UTF8, /* iPrefEnc */ 0, /* flags */ 0, /* pUserData */ 0, /* pNext */ stat3Init, /* xFunc */ 0, /* xStep */ 0, /* xFinalize */ "stat3_init", /* zName */ 0, /* pHash */ 0 /* pDestructor */ }; /* ** Implementation of the stat3_push(nEq,nLt,nDLt,rowid,P) SQL function. The ** arguments describe a single key instance. This routine makes the ** decision about whether or not to retain this key for the sqlite_stat3 ** table. ** ** The return value is NULL. */ static void stat3Push( sqlite3_context *context, int argc, sqlite3_value **argv ){ Stat3Accum *p = (Stat3Accum*)sqlite3_value_blob(argv[4]); tRowcnt nEq = sqlite3_value_int64(argv[0]); tRowcnt nLt = sqlite3_value_int64(argv[1]); tRowcnt nDLt = sqlite3_value_int64(argv[2]); i64 rowid = sqlite3_value_int64(argv[3]); u8 isPSample = 0; u8 doInsert = 0; int iMin = p->iMin; struct Stat3Sample *pSample; int i; u32 h; UNUSED_PARAMETER(context); UNUSED_PARAMETER(argc); if( nEq==0 ) return; h = p->iPrn = p->iPrn*1103515245 + 12345; if( (nLt/p->nPSample)!=((nEq+nLt)/p->nPSample) ){ doInsert = isPSample = 1; }else if( p->nSamplemxSample ){ doInsert = 1; }else{ if( nEq>p->a[iMin].nEq || (nEq==p->a[iMin].nEq && h>p->a[iMin].iHash) ){ doInsert = 1; } } if( !doInsert ) return; if( p->nSample==p->mxSample ){ assert( p->nSample - iMin - 1 >= 0 ); memmove(&p->a[iMin], &p->a[iMin+1], sizeof(p->a[0])*(p->nSample-iMin-1)); pSample = &p->a[p->nSample-1]; }else{ pSample = &p->a[p->nSample++]; } pSample->iRowid = rowid; pSample->nEq = nEq; pSample->nLt = nLt; pSample->nDLt = nDLt; pSample->iHash = h; pSample->isPSample = isPSample; /* Find the new minimum */ if( p->nSample==p->mxSample ){ pSample = p->a; i = 0; while( pSample->isPSample ){ i++; pSample++; assert( inSample ); } nEq = pSample->nEq; h = pSample->iHash; iMin = i; for(i++, pSample++; inSample; i++, pSample++){ if( pSample->isPSample ) continue; if( pSample->nEqnEq==nEq && pSample->iHashnEq; h = pSample->iHash; } } p->iMin = iMin; } } static const FuncDef stat3PushFuncdef = { 5, /* nArg */ SQLITE_UTF8, /* iPrefEnc */ 0, /* flags */ 0, /* pUserData */ 0, /* pNext */ stat3Push, /* xFunc */ 0, /* xStep */ 0, /* xFinalize */ "stat3_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 stat3Get( sqlite3_context *context, int argc, sqlite3_value **argv ){ int n = sqlite3_value_int(argv[1]); Stat3Accum *p = (Stat3Accum*)sqlite3_value_blob(argv[0]); assert( p!=0 ); if( p->nSample<=n ) return; switch( argc ){ case 2: sqlite3_result_int64(context, p->a[n].iRowid); break; case 3: sqlite3_result_int64(context, p->a[n].nEq); break; case 4: sqlite3_result_int64(context, p->a[n].nLt); break; default: sqlite3_result_int64(context, p->a[n].nDLt); break; } } static const FuncDef stat3GetFuncdef = { -1, /* nArg */ SQLITE_UTF8, /* iPrefEnc */ 0, /* flags */ 0, /* pUserData */ 0, /* pNext */ stat3Get, /* xFunc */ 0, /* xStep */ 0, /* xFinalize */ "stat3_get", /* zName */ 0, /* pHash */ 0 /* pDestructor */ }; #endif /* SQLITE_ENABLE_STAT3 */ /* ** 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 */ 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_STAT3 int regNumEq = regStat1; /* Number of instances. Same as regStat1 */ int regNumLt = iMem++; /* Number of keys less than regSample */ int regNumDLt = iMem++; /* Number of distinct keys less than regSample */ int regSample = iMem++; /* The next sample value */ int regRowid = regSample; /* Rowid of a sample */ int regAccum = iMem++; /* Register to hold Stat3Accum object */ 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 */ 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( memcmp(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; KeyInfo *pKey; int addrIfNot = 0; /* address of OP_IfNot */ int *aChngAddr; /* Array of jump instruction addresses */ if( pOnlyIdx && pOnlyIdx!=pIdx ) continue; 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); if( iMem+1+(nCol*2)>pParse->nMem ){ pParse->nMem = iMem+1+(nCol*2); } /* 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_STAT3 if( once ){ once = 0; sqlite3OpenTable(pParse, iTabCur, iDb, pTab, OP_OpenRead); } sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regCount); sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_STAT3_SAMPLES, regTemp1); sqlite3VdbeAddOp2(v, OP_Integer, 0, regNumEq); sqlite3VdbeAddOp2(v, OP_Integer, 0, regNumLt); sqlite3VdbeAddOp2(v, OP_Integer, -1, regNumDLt); sqlite3VdbeAddOp4(v, OP_Function, 1, regCount, regAccum, (char*)&stat3InitFuncdef, P4_FUNCDEF); sqlite3VdbeChangeP5(v, 2); #endif /* SQLITE_ENABLE_STAT3 */ /* The block of memory cells initialized here is used as follows. ** ** iMem: ** The total number of rows in the table. ** ** iMem+1 .. iMem+nCol: ** Number of distinct entries in index 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. */ for(i=0; i<=nCol; i++){ sqlite3VdbeAddOp2(v, OP_Integer, 0, iMem+i); } for(i=0; iazColl!=0 ); assert( pIdx->azColl[i]!=0 ); pColl = sqlite3LocateCollSeq(pParse, pIdx->azColl[i]); aChngAddr[i] = sqlite3VdbeAddOp4(v, OP_Ne, regCol, 0, iMem+nCol+i+1, (char*)pColl, P4_COLLSEQ); sqlite3VdbeChangeP5(v, SQLITE_NULLEQ); VdbeComment((v, "jump if column %d changed", i)); #ifdef SQLITE_ENABLE_STAT3 if( i==0 ){ sqlite3VdbeAddOp2(v, OP_AddImm, regNumEq, 1); VdbeComment((v, "incr repeat count")); } #endif } sqlite3VdbeAddOp2(v, OP_Goto, 0, endOfLoop); for(i=0; inColumn, regRowid); sqlite3VdbeAddOp3(v, OP_Add, regNumEq, regNumLt, regNumLt); sqlite3VdbeAddOp2(v, OP_AddImm, regNumDLt, 1); sqlite3VdbeAddOp2(v, OP_Integer, 1, regNumEq); #endif } sqlite3VdbeAddOp2(v, OP_AddImm, iMem+i+1, 1); sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, iMem+nCol+i+1); } sqlite3DbFree(db, aChngAddr); /* 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); #ifdef SQLITE_ENABLE_STAT3 sqlite3VdbeAddOp4(v, OP_Function, 1, regNumEq, regTemp2, (char*)&stat3PushFuncdef, P4_FUNCDEF); sqlite3VdbeChangeP5(v, 5); sqlite3VdbeAddOp2(v, OP_Integer, -1, regLoop); shortJump = sqlite3VdbeAddOp2(v, OP_AddImm, regLoop, 1); sqlite3VdbeAddOp4(v, OP_Function, 1, regAccum, regTemp1, (char*)&stat3GetFuncdef, P4_FUNCDEF); sqlite3VdbeChangeP5(v, 2); sqlite3VdbeAddOp1(v, OP_IsNull, regTemp1); sqlite3VdbeAddOp3(v, OP_NotExists, iTabCur, shortJump, regTemp1); sqlite3VdbeAddOp3(v, OP_Column, iTabCur, pIdx->aiColumn[0], regSample); sqlite3ColumnDefault(v, pTab, pIdx->aiColumn[0], regSample); sqlite3VdbeAddOp4(v, OP_Function, 1, regAccum, regNumEq, (char*)&stat3GetFuncdef, P4_FUNCDEF); sqlite3VdbeChangeP5(v, 3); sqlite3VdbeAddOp4(v, OP_Function, 1, regAccum, regNumLt, (char*)&stat3GetFuncdef, P4_FUNCDEF); sqlite3VdbeChangeP5(v, 4); sqlite3VdbeAddOp4(v, OP_Function, 1, regAccum, regNumDLt, (char*)&stat3GetFuncdef, P4_FUNCDEF); sqlite3VdbeChangeP5(v, 5); sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 6, regRec, "bbbbbb", 0); sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regNewRowid); sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regRec, regNewRowid); sqlite3VdbeAddOp2(v, OP_Goto, 0, shortJump); 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, iMem, regStat1); if( jZeroRows<0 ){ jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, iMem); } for(i=0; ipIndex==0 ){ 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); }else{ sqlite3VdbeJumpHere(v, jZeroRows); jZeroRows = sqlite3VdbeAddOp0(v, OP_Goto); } 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); if( pParse->nMemnMem = regRec; sqlite3VdbeJumpHere(v, jZeroRows); } /* ** 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 -- 2 ** ANALYZE ?.? -- 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; inDb; 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; }; /* ** 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; int i, c, n; tRowcnt v; 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; } n = pIndex ? pIndex->nColumn : 0; z = argv[2]; for(i=0; *z && i<=n; i++){ v = 0; while( (c=z[0])>='0' && c<='9' ){ v = v*10 + c - '0'; z++; } if( i==0 ) pTable->nRowEst = v; if( pIndex==0 ) break; pIndex->aiRowEst[i] = v; if( *z==' ' ) z++; if( memcmp(z, "unordered", 10)==0 ){ pIndex->bUnordered = 1; break; } } 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_STAT3 if( pIdx->aSample ){ int j; for(j=0; jnSample; j++){ IndexSample *p = &pIdx->aSample[j]; if( p->eType==SQLITE_TEXT || p->eType==SQLITE_BLOB ){ sqlite3DbFree(db, p->u.z); } } 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_STAT3 /* ** Load content from the sqlite_stat3 table into the Index.aSample[] ** arrays of all indices. */ static int loadStat3(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 */ int eType; /* Datatype of a sample */ IndexSample *pSample; /* A slot in pIdx->aSample[] */ if( !sqlite3FindTable(db, "sqlite_stat3", zDb) ){ return SQLITE_OK; } zSql = sqlite3MPrintf(db, "SELECT idx,count(*) FROM %Q.sqlite_stat3" " 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 */ 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; pIdx->aSample = sqlite3MallocZero( nSample*sizeof(IndexSample) ); pIdx->avgEq = pIdx->aiRowEst[1]; if( pIdx->aSample==0 ){ db->mallocFailed = 1; sqlite3_finalize(pStmt); return SQLITE_NOMEM; } } rc = sqlite3_finalize(pStmt); if( rc ) return rc; zSql = sqlite3MPrintf(db, "SELECT idx,neq,nlt,ndlt,sample FROM %Q.sqlite_stat3", 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 */ 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( idxnSample ); pSample = &pIdx->aSample[idx]; pSample->nEq = (tRowcnt)sqlite3_column_int64(pStmt, 1); pSample->nLt = (tRowcnt)sqlite3_column_int64(pStmt, 2); pSample->nDLt = (tRowcnt)sqlite3_column_int64(pStmt, 3); if( idx==pIdx->nSample-1 ){ if( pSample->nDLt>0 ){ for(i=0, sumEq=0; i<=idx-1; i++) sumEq += pIdx->aSample[i].nEq; pIdx->avgEq = (pSample->nLt - sumEq)/pSample->nDLt; } if( pIdx->avgEq<=0 ) pIdx->avgEq = 1; } eType = sqlite3_column_type(pStmt, 4); pSample->eType = (u8)eType; switch( eType ){ case SQLITE_INTEGER: { pSample->u.i = sqlite3_column_int64(pStmt, 4); break; } case SQLITE_FLOAT: { pSample->u.r = sqlite3_column_double(pStmt, 4); break; } case SQLITE_NULL: { break; } default: assert( eType==SQLITE_TEXT || eType==SQLITE_BLOB ); { const char *z = (const char *)( (eType==SQLITE_BLOB) ? sqlite3_column_blob(pStmt, 4): sqlite3_column_text(pStmt, 4) ); int n = z ? sqlite3_column_bytes(pStmt, 4) : 0; pSample->nByte = n; if( n < 1){ pSample->u.z = 0; }else{ pSample->u.z = sqlite3Malloc(n); if( pSample->u.z==0 ){ db->mallocFailed = 1; sqlite3_finalize(pStmt); return SQLITE_NOMEM; } memcpy(pSample->u.z, z, n); } } } } return sqlite3_finalize(pStmt); } #endif /* SQLITE_ENABLE_STAT3 */ /* ** Load the content of the sqlite_stat1 and sqlite_stat3 tables. The ** contents of sqlite_stat1 are used to populate the Index.aiRowEst[] ** arrays. The contents of sqlite_stat3 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_STAT3 was defined ** during compilation and the sqlite_stat3 table is present, no data is ** read from it. ** ** If SQLITE_ENABLE_STAT3 was defined during compilation and the ** sqlite_stat3 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 && iDbnDb ); 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_STAT3 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_stat3 table. */ #ifdef SQLITE_ENABLE_STAT3 if( rc==SQLITE_OK ){ rc = loadStat3(db, sInfo.zDatabase); } #endif if( rc==SQLITE_NOMEM ){ db->mallocFailed = 1; } return rc; } #endif /* SQLITE_OMIT_ANALYZE */