/*
** This function is called to generate code executed when a row is deleted
** from the parent table of foreign key constraint pFKey and, if pFKey is
** deferred, when a row is inserted into the same table. When generating
** code for an SQL UPDATE operation, this function may be called twice -
** once to "delete" the old row and once to "insert" the new row.
**
** The code generated by this function scans through the rows in the child
** table that correspond to the parent table row being deleted or inserted.
** For each child row found, one of the following actions is taken:
**
** Operation | FK type | Action taken
** --------------------------------------------------------------------------
** DELETE immediate Increment the "immediate constraint counter".
** Or, if the ON (UPDATE|DELETE) action is RESTRICT,
** throw a "foreign key constraint failed" exception.
**
** INSERT immediate Decrement the "immediate constraint counter".
**
** DELETE deferred Increment the "deferred constraint counter".
** Or, if the ON (UPDATE|DELETE) action is RESTRICT,
** throw a "foreign key constraint failed" exception.
**
** INSERT deferred Decrement the "deferred constraint counter".
**
** These operations are identified in the comment at the top of this file
** (fkey.c) as "I.2" and "D.2".
*/
static void fkScanChildren(
Parse *pParse, /* Parse context */
SrcList *pSrc, /* SrcList containing the table to scan */
Table *pTab,
Index *pIdx, /* Foreign key index */
FKey *pFKey, /* Foreign key relationship */
int *aiCol, /* Map from pIdx cols to child table cols */
int regData, /* Referenced table data starts here */
int nIncr /* Amount to increment deferred counter by */
){
sqlite3 *db = pParse->db; /* Database handle */
int i; /* Iterator variable */
Expr *pWhere = 0; /* WHERE clause to scan with */
NameContext sNameContext; /* Context used to resolve WHERE clause */
WhereInfo *pWInfo; /* Context used by sqlite3WhereXXX() */
int iFkIfZero = 0; /* Address of OP_FkIfZero */
Vdbe *v = sqlite3GetVdbe(pParse);
assert( !pIdx || pIdx->pTable==pTab );
if( nIncr<0 ){
iFkIfZero = sqlite3VdbeAddOp2(v, OP_FkIfZero, pFKey->isDeferred, 0);
}
/* Create an Expr object representing an SQL expression like:
**
** <parent-key1> = <child-key1> AND <parent-key2> = <child-key2> ...
**
** The collation sequence used for the comparison should be that of
** the parent key columns. The affinity of the parent key column should
** be applied to each child key value before the comparison takes place.
*/
for(i=0; i<pFKey->nCol; i++){
Expr *pLeft; /* Value from parent table row */
Expr *pRight; /* Column ref to child table */
Expr *pEq; /* Expression (pLeft = pRight) */
int iCol; /* Index of column in child table */
const char *zCol; /* Name of column in child table */
pLeft = sqlite3Expr(db, TK_REGISTER, 0);
if( pLeft ){
/* Set the collation sequence and affinity of the LHS of each TK_EQ
** expression to the parent key column defaults. */
if( pIdx ){
Column *pCol;
iCol = pIdx->aiColumn[i];
pCol = &pTab->aCol[iCol];
if( pTab->iPKey==iCol ) iCol = -1;
pLeft->iTable = regData+iCol+1;
pLeft->affinity = pCol->affinity;
pLeft->pColl = sqlite3LocateCollSeq(pParse, pCol->zColl);
}else{
pLeft->iTable = regData;
pLeft->affinity = SQLITE_AFF_INTEGER;
}
}
iCol = aiCol ? aiCol[i] : pFKey->aCol[0].iFrom;
assert( iCol>=0 );
zCol = pFKey->pFrom->aCol[iCol].zName;
pRight = sqlite3Expr(db, TK_ID, zCol);
pEq = sqlite3PExpr(pParse, TK_EQ, pLeft, pRight, 0);
pWhere = sqlite3ExprAnd(db, pWhere, pEq);
}
/* If the child table is the same as the parent table, and this scan
** is taking place as part of a DELETE operation (operation D.2), omit the
** row being deleted from the scan by adding ($rowid != rowid) to the WHERE
** clause, where $rowid is the rowid of the row being deleted. */
if( pTab==pFKey->pFrom && nIncr>0 ){
Expr *pEq; /* Expression (pLeft = pRight) */
Expr *pLeft; /* Value from parent table row */
Expr *pRight; /* Column ref to child table */
pLeft = sqlite3Expr(db, TK_REGISTER, 0);
pRight = sqlite3Expr(db, TK_COLUMN, 0);
if( pLeft && pRight ){
pLeft->iTable = regData;
pLeft->affinity = SQLITE_AFF_INTEGER;
pRight->iTable = pSrc->a[0].iCursor;
pRight->iColumn = -1;
}
pEq = sqlite3PExpr(pParse, TK_NE, pLeft, pRight, 0);
pWhere = sqlite3ExprAnd(db, pWhere, pEq);
}
/* Resolve the references in the WHERE clause. */
memset(&sNameContext, 0, sizeof(NameContext));
sNameContext.pSrcList = pSrc;
sNameContext.pParse = pParse;
sqlite3ResolveExprNames(&sNameContext, pWhere);
/* Create VDBE to loop through the entries in pSrc that match the WHERE
** clause. If the constraint is not deferred, throw an exception for
** each row found. Otherwise, for deferred constraints, increment the
** deferred constraint counter by nIncr for each row selected. */
pWInfo = sqlite3WhereBegin(pParse, pSrc, pWhere, 0, 0, 0);
if( nIncr>0 && pFKey->isDeferred==0 ){
sqlite3ParseToplevel(pParse)->mayAbort = 1;
}
sqlite3VdbeAddOp2(v, OP_FkCounter, pFKey->isDeferred, nIncr);
if( pWInfo ){
sqlite3WhereEnd(pWInfo);
}
/* Clean up the WHERE clause constructed above. */
sqlite3ExprDelete(db, pWhere);
if( iFkIfZero ){
sqlite3VdbeJumpHere(v, iFkIfZero);
}
}
/*
** 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 regSampleno = iMem++; /* Register containing next sample number */
int regCol = iMem++; /* Content of a column analyzed table */
int regRec = iMem++; /* Register holding completed record */
int regTemp = iMem++; /* Temporary use register */
int regRowid = iMem++; /* Rowid for the inserted record */
#ifdef SQLITE_ENABLE_STAT2
int addr = 0; /* Instruction address */
int regTemp2 = iMem++; /* Temporary use register */
int regSamplerecno = iMem++; /* Index of next sample to record */
int regRecno = iMem++; /* Current sample index */
int regLast = iMem++; /* Index of last sample to record */
int regFirst = iMem++; /* Index of first sample to record */
#endif
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;
if( pOnlyIdx && pOnlyIdx!=pIdx ) continue;
nCol = pIdx->nColumn;
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_STAT2
/* If this iteration of the loop is generating code to analyze the
** first index in the pTab->pIndex list, then register regLast has
** not been populated. In this case populate it now. */
if( pTab->pIndex==pIdx ){
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES, regSamplerecno);
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES*2-1, regTemp);
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES*2, regTemp2);
sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regLast);
sqlite3VdbeAddOp2(v, OP_Null, 0, regFirst);
addr = sqlite3VdbeAddOp3(v, OP_Lt, regSamplerecno, 0, regLast);
sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regLast, regFirst);
sqlite3VdbeAddOp3(v, OP_Multiply, regLast, regTemp, regLast);
sqlite3VdbeAddOp2(v, OP_AddImm, regLast, SQLITE_INDEX_SAMPLES*2-2);
sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regLast, regLast);
sqlite3VdbeJumpHere(v, addr);
}
/* Zero the regSampleno and regRecno registers. */
sqlite3VdbeAddOp2(v, OP_Integer, 0, regSampleno);
sqlite3VdbeAddOp2(v, OP_Integer, 0, regRecno);
sqlite3VdbeAddOp2(v, OP_Copy, regFirst, regSamplerecno);
#endif
/* 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; i<nCol; i++){
sqlite3VdbeAddOp2(v, OP_Null, 0, iMem+nCol+i+1);
}
/* Start the analysis loop. This loop runs through all the entries in
** the index b-tree. */
endOfLoop = sqlite3VdbeMakeLabel(v);
sqlite3VdbeAddOp2(v, OP_Rewind, iIdxCur, endOfLoop);
topOfLoop = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_AddImm, iMem, 1);
for(i=0; i<nCol; i++){
CollSeq *pColl;
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, regCol);
if( i==0 ){
#ifdef SQLITE_ENABLE_STAT2
/* Check if the record that cursor iIdxCur points to contains a
** value that should be stored in the sqlite_stat2 table. If so,
** store it. */
int ne = sqlite3VdbeAddOp3(v, OP_Ne, regRecno, 0, regSamplerecno);
assert( regTabname+1==regIdxname
&& regTabname+2==regSampleno
&& regTabname+3==regCol
);
sqlite3VdbeChangeP5(v, SQLITE_JUMPIFNULL);
sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 4, regRec, "aaab", 0);
sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur+1, regRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iStatCur+1, regRec, regRowid);
/* Calculate new values for regSamplerecno and regSampleno.
**
** sampleno = sampleno + 1
** samplerecno = samplerecno+(remaining records)/(remaining samples)
*/
sqlite3VdbeAddOp2(v, OP_AddImm, regSampleno, 1);
sqlite3VdbeAddOp3(v, OP_Subtract, regRecno, regLast, regTemp);
sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
sqlite3VdbeAddOp2(v, OP_Integer, SQLITE_INDEX_SAMPLES, regTemp2);
sqlite3VdbeAddOp3(v, OP_Subtract, regSampleno, regTemp2, regTemp2);
sqlite3VdbeAddOp3(v, OP_Divide, regTemp2, regTemp, regTemp);
sqlite3VdbeAddOp3(v, OP_Add, regSamplerecno, regTemp, regSamplerecno);
sqlite3VdbeJumpHere(v, ne);
sqlite3VdbeAddOp2(v, OP_AddImm, regRecno, 1);
#endif
/* Always record the very first row */
sqlite3VdbeAddOp1(v, OP_IfNot, iMem+1);
}
assert( pIdx->azColl!=0 );
assert( pIdx->azColl[i]!=0 );
pColl = sqlite3LocateCollSeq(pParse, pIdx->azColl[i]);
sqlite3VdbeAddOp4(v, OP_Ne, regCol, 0, iMem+nCol+i+1,
(char*)pColl, P4_COLLSEQ);
sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
}
if( db->mallocFailed ){
/* If a malloc failure has occurred, then the result of the expression
** passed as the second argument to the call to sqlite3VdbeJumpHere()
** below may be negative. Which causes an assert() to fail (or an
** out-of-bounds write if SQLITE_DEBUG is not defined). */
return;
}
sqlite3VdbeAddOp2(v, OP_Goto, 0, endOfLoop);
for(i=0; i<nCol; i++){
int addr2 = sqlite3VdbeCurrentAddr(v) - (nCol*2);
if( i==0 ){
sqlite3VdbeJumpHere(v, addr2-1); /* Set jump dest for the OP_IfNot */
}
sqlite3VdbeJumpHere(v, addr2); /* Set jump dest for the OP_Ne */
sqlite3VdbeAddOp2(v, OP_AddImm, iMem+i+1, 1);
sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, i, iMem+nCol+i+1);
}
/* End of the analysis loop. */
sqlite3VdbeResolveLabel(v, endOfLoop);
sqlite3VdbeAddOp2(v, OP_Next, iIdxCur, topOfLoop);
sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
/* 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, regSampleno);
if( jZeroRows<0 ){
jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, iMem);
}
for(i=0; i<nCol; i++){
sqlite3VdbeAddOp4(v, OP_String8, 0, regTemp, 0, " ", 0);
sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
sqlite3VdbeAddOp3(v, OP_Add, iMem, iMem+i+1, regTemp);
sqlite3VdbeAddOp2(v, OP_AddImm, regTemp, -1);
sqlite3VdbeAddOp3(v, OP_Divide, iMem+i+1, regTemp, regTemp);
sqlite3VdbeAddOp1(v, OP_ToInt, regTemp);
sqlite3VdbeAddOp3(v, OP_Concat, regTemp, regSampleno, regSampleno);
}
sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regRec, "aaa", 0);
sqlite3VdbeAddOp2(v, OP_NewRowid, iStatCur, regRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regRowid);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
}
/* If the table has no indices, create a single sqlite_stat1 entry
** containing NULL as the index name and the row count as the content.
*/
if( pTab->pIndex==0 ){
sqlite3VdbeAddOp3(v, OP_OpenRead, iIdxCur, pTab->tnum, iDb);
VdbeComment((v, "%s", pTab->zName));
sqlite3VdbeAddOp2(v, OP_Count, iIdxCur, regSampleno);
sqlite3VdbeAddOp1(v, OP_Close, iIdxCur);
jZeroRows = sqlite3VdbeAddOp1(v, OP_IfNot, regSampleno);
}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, regRowid);
sqlite3VdbeAddOp3(v, OP_Insert, iStatCur, regRec, regRowid);
sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
if( pParse->nMem<regRec ) pParse->nMem = regRec;
sqlite3VdbeJumpHere(v, jZeroRows);
}