diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/vdbeaux.c | 40 |
1 files changed, 32 insertions, 8 deletions
diff --git a/src/vdbeaux.c b/src/vdbeaux.c index b682d833d..d7c162524 100644 --- a/src/vdbeaux.c +++ b/src/vdbeaux.c @@ -1041,18 +1041,21 @@ void sqlite3VdbeFrameDelete(VdbeFrame *p){ ** 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; /* Total number of rows to return */ + 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; - sqlite3 *db = p->db; - int i; - int rc = SQLITE_OK; - Mem *pMem = p->pResultSet = &p->aMem[1]; + 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 ); @@ -1072,12 +1075,24 @@ int sqlite3VdbeList( return SQLITE_ERROR; } - /* Figure out total number of rows that will be returned by this - ** EXPLAIN program. */ + /* 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; } @@ -1100,8 +1115,12 @@ int sqlite3VdbeList( 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++){ @@ -1123,6 +1142,11 @@ int sqlite3VdbeList( 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; |