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Overview
Comment: | Add comments and an assert() to help clarify the operation of the sqlite3VdbeList() routine used to implement EXPLAIN. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
e1ccdb93d79a6f7b16f1f59cc3ad78f8 |
User & Date: | drh 2009-12-31 20:35:08.000 |
Context
2010-01-01
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18:57 | Add evidence marks associated with autoincrement. (check-in: 0e918c5489 user: drh tags: trunk) | |
2009-12-31
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20:35 | Add comments and an assert() to help clarify the operation of the sqlite3VdbeList() routine used to implement EXPLAIN. (check-in: e1ccdb93d7 user: drh tags: trunk) | |
19:48 | Minor changes to test scripts to support various SQLITE_OMIT options. (check-in: 97f8a886b6 user: shaneh tags: trunk) | |
Changes
Changes to src/vdbeaux.c.
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1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 | ** running the code, it invokes the callback once for each instruction. ** This feature is used to implement "EXPLAIN". ** ** When p->explain==1, each instruction is listed. When ** p->explain==2, only OP_Explain instructions are listed and these ** are shown in a different format. p->explain==2 is used to implement ** EXPLAIN QUERY PLAN. */ int sqlite3VdbeList( Vdbe *p /* The VDBE */ ){ | > > > | | | | | | > > > | | > > > > > > > > > | 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 | ** running the code, it invokes the callback once for each instruction. ** This feature is used to implement "EXPLAIN". ** ** When p->explain==1, each instruction is listed. When ** p->explain==2, only OP_Explain instructions are listed and these ** are shown in a different format. p->explain==2 is used to implement ** EXPLAIN QUERY PLAN. ** ** When p->explain==1, first the main program is listed, then each of ** the trigger subprograms are listed one by one. */ int sqlite3VdbeList( Vdbe *p /* The VDBE */ ){ int nRow; /* Stop when row count reaches this */ int nSub = 0; /* Number of sub-vdbes seen so far */ SubProgram **apSub = 0; /* Array of sub-vdbes */ Mem *pSub = 0; /* Memory cell hold array of subprogs */ sqlite3 *db = p->db; /* The database connection */ int i; /* Loop counter */ int rc = SQLITE_OK; /* Return code */ Mem *pMem = p->pResultSet = &p->aMem[1]; /* First Mem of result set */ assert( p->explain ); assert( p->magic==VDBE_MAGIC_RUN ); assert( db->magic==SQLITE_MAGIC_BUSY ); assert( p->rc==SQLITE_OK || p->rc==SQLITE_BUSY || p->rc==SQLITE_NOMEM ); /* Even though this opcode does not use dynamic strings for ** the result, result columns may become dynamic if the user calls ** sqlite3_column_text16(), causing a translation to UTF-16 encoding. */ releaseMemArray(pMem, 8); if( p->rc==SQLITE_NOMEM ){ /* This happens if a malloc() inside a call to sqlite3_column_text() or ** sqlite3_column_text16() failed. */ db->mallocFailed = 1; return SQLITE_ERROR; } /* When the number of output rows reaches nRow, that means the ** listing has finished and sqlite3_step() should return SQLITE_DONE. ** nRow is the sum of the number of rows in the main program, plus ** the sum of the number of rows in all trigger subprograms encountered ** so far. The nRow value will increase as new trigger subprograms are ** encountered, but p->pc will eventually catch up to nRow. */ nRow = p->nOp; if( p->explain==1 ){ /* The first 8 memory cells are used for the result set. So we will ** commandeer the 9th cell to use as storage for an array of pointers ** to trigger subprograms. The VDBE is guaranteed to have at least 9 ** cells. */ assert( p->nMem>9 ); pSub = &p->aMem[9]; if( pSub->flags&MEM_Blob ){ /* On the first call to sqlite3_step(), pSub will hold a NULL. It is ** initialized to a BLOB by the P4_SUBPROGRAM processing logic below */ nSub = pSub->n/sizeof(Vdbe*); apSub = (SubProgram **)pSub->z; } for(i=0; i<nSub; i++){ nRow += apSub[i]->nOp; } } |
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1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 | p->rc = SQLITE_INTERRUPT; rc = SQLITE_ERROR; sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3ErrStr(p->rc)); }else{ char *z; Op *pOp; if( i<p->nOp ){ pOp = &p->aOp[i]; }else{ int j; i -= p->nOp; for(j=0; i>=apSub[j]->nOp; j++){ i -= apSub[j]->nOp; } pOp = &apSub[j]->aOp[i]; } | > > > > | 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 | p->rc = SQLITE_INTERRUPT; rc = SQLITE_ERROR; sqlite3SetString(&p->zErrMsg, db, "%s", sqlite3ErrStr(p->rc)); }else{ char *z; Op *pOp; if( i<p->nOp ){ /* The output line number is small enough that we are still in the ** main program. */ pOp = &p->aOp[i]; }else{ /* We are currently listing subprograms. Figure out which one and ** pick up the appropriate opcode. */ int j; i -= p->nOp; for(j=0; i>=apSub[j]->nOp; j++){ i -= apSub[j]->nOp; } pOp = &apSub[j]->aOp[i]; } |
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1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 | pMem->z = (char*)sqlite3OpcodeName(pOp->opcode); /* Opcode */ assert( pMem->z!=0 ); pMem->n = sqlite3Strlen30(pMem->z); pMem->type = SQLITE_TEXT; pMem->enc = SQLITE_UTF8; pMem++; if( pOp->p4type==P4_SUBPROGRAM ){ int nByte = (nSub+1)*sizeof(SubProgram*); int j; for(j=0; j<nSub; j++){ if( apSub[j]==pOp->p4.pProgram ) break; } if( j==nSub && SQLITE_OK==sqlite3VdbeMemGrow(pSub, nByte, 1) ){ | > > > > > | 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 | pMem->z = (char*)sqlite3OpcodeName(pOp->opcode); /* Opcode */ assert( pMem->z!=0 ); pMem->n = sqlite3Strlen30(pMem->z); pMem->type = SQLITE_TEXT; pMem->enc = SQLITE_UTF8; pMem++; /* When an OP_Program opcode is encounter (the only opcode that has ** a P4_SUBPROGRAM argument), expand the size of the array of subprograms ** kept in p->aMem[9].z to hold the new program - assuming this subprogram ** has not already been seen. */ if( pOp->p4type==P4_SUBPROGRAM ){ int nByte = (nSub+1)*sizeof(SubProgram*); int j; for(j=0; j<nSub; j++){ if( apSub[j]==pOp->p4.pProgram ) break; } if( j==nSub && SQLITE_OK==sqlite3VdbeMemGrow(pSub, nByte, 1) ){ |
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