mirrors/sqlite
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Improved comments on foreign key logic.

Browse Source 
FossilOrigin-Name: 1315d9109c7105f4a62bb2d43ca6948d41245129
This commit is contained in:
drh 2013-11-03 02:27:58 +00:00
parent 2552d43f4c
commit bd50a926ef
5 changed files with 47 additions and 36 deletions

16
manifest

@ -1,5 +1,5 @@
C Improved\sSynopsis\son\sregister\scomparison\soperators.\s\sFix\sa\sbug\son\sthe\nconstraint\scheck\sgenerator.
D 2013-11-02T22:29:34.665
C Improved\scomments\son\sforeign\skey\slogic.
D 2013-11-03T02:27:58.561
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in 0522b53cdc1fcfc18f3a98e0246add129136c654
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@ -168,7 +168,7 @@ F src/btmutex.c 976f45a12e37293e32cae0281b15a21d48a8aaa7
F src/btree.c 509722ce305471b626d3401c0631a808fd33237b
F src/btree.h bfe0e8c5759b4ec77b0d18390064a6ef3cdffaaf
F src/btreeInt.h f038e818bfadf75afbd09819ed93c26a333d39e0
F src/build.c 113a23bc6f8cf81dd03c984ef0460cca89c48f2e
F src/build.c 21727e787a763e2a9981297eff7945374eaffc19
F src/callback.c f99a8957ba2adf369645fac0db09ad8adcf1caa2
F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
F src/ctime.c ea4b7f3623a0fcb1146e7f245d7410033e86859c
@ -176,7 +176,7 @@ F src/date.c 593c744b2623971e45affd0bde347631bdfa4625
F src/delete.c 605be39dc72a56768a55ee7245d92774ed7ae343
F src/expr.c ecc2b98eb75fe5533cfdfcca6b04cfe5f0c6001f
F src/fault.c 160a0c015b6c2629d3899ed2daf63d75754a32bb
F src/fkey.c 8dc2b14dd93cd991629ce98e02bc4a5a181f7146
F src/fkey.c df809cab5485c16ab146cc13246afd41900ece84
F src/func.c 2c47b65e6e00e3e9374942f28254faf8adafe398
F src/global.c 5caf4deab621abb45b4c607aad1bd21c20aac759
F src/hash.c ac3470bbf1ca4ae4e306a8ecb0fdf1731810ffe4
@ -223,7 +223,7 @@ F src/shell.c 03d8d9b4052430343ff30d646334621f980f1202
F src/sqlite.h.in 547a44dd4ff4d975e92a645ea2d609e543a83d0f
F src/sqlite3.rc 11094cc6a157a028b301a9f06b3d03089ea37c3e
F src/sqlite3ext.h 886f5a34de171002ad46fae8c36a7d8051c190fc
F src/sqliteInt.h 7cc1b32804563f26cf44a4a48ad370490c8f737c
F src/sqliteInt.h 0d272caa9b943c7e20b9c9924c6d793aece6ee0d
F src/sqliteLimit.h 164b0e6749d31e0daa1a4589a169d31c0dec7b3d
F src/status.c 7ac05a5c7017d0b9f0b4bcd701228b784f987158
F src/table.c 2cd62736f845d82200acfa1287e33feb3c15d62e
@ -1130,7 +1130,7 @@ F tool/vdbe-compress.tcl f12c884766bd14277f4fcedcae07078011717381
F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
P 39e32187b66405e00dbd44685f6cdd269c90f5e5
R 58e9f12157086c3e22220529477830cd
P a7a18b65fa34dfdf6117fa21db3e576f96876617
R c871a047a9d8bb37aa43632b24cb0302
U drh
Z 72d46f91118ca7659eef125e3fbe4980
Z 938c2bb15557c0ae50def104b2712b1c

2
manifest.uuid

@ -1 +1 @@
a7a18b65fa34dfdf6117fa21db3e576f96876617
1315d9109c7105f4a62bb2d43ca6948d41245129

4
src/build.c

@ -2466,8 +2466,8 @@ exit_drop_table:
** currently under construction. pFromCol determines which columns
** in the current table point to the foreign key. If pFromCol==0 then
** connect the key to the last column inserted. pTo is the name of
** the table referred to. pToCol is a list of tables in the other
** pTo table that the foreign key points to. flags contains all
** the table referred to (a.k.a the "parent" table). pToCol is a list
** of tables in the parent pTo table. flags contains all
** information about the conflict resolution algorithms specified
** in the ON DELETE, ON UPDATE and ON INSERT clauses.
**

32
src/fkey.c

@ -475,12 +475,12 @@ static void fkLookupParent(
*/
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 */
SrcList *pSrc, /* The child table to be scanned */
Table *pTab, /* The parent table */
Index *pIdx, /* Index on parent covering the foreign key */
FKey *pFKey, /* The foreign key linking pSrc to pTab */
int *aiCol, /* Map from pIdx cols to child table cols */
int regData, /* Referenced table data starts here */
int regData, /* Parent row data starts here */
int nIncr /* Amount to increment deferred counter by */
){
sqlite3 *db = pParse->db; /* Database handle */
@ -491,7 +491,9 @@ static void fkScanChildren(
int iFkIfZero = 0; /* Address of OP_FkIfZero */
Vdbe *v = sqlite3GetVdbe(pParse);
assert( !pIdx || pIdx->pTable==pTab );
assert( pIdx==0 || pIdx->pTable==pTab );
assert( pIdx==0 || pIdx->nKeyCol==pFKey->nCol );
assert( pIdx!=0 || pFKey->nCol==1 );
if( nIncr<0 ){
iFkIfZero = sqlite3VdbeAddOp2(v, OP_FkIfZero, pFKey->isDeferred, 0);
@ -545,7 +547,7 @@ static void fkScanChildren(
** 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 && HasRowid(pTab) /*FIXME*/ ){
Expr *pEq; /* Expression (pLeft = pRight) */
Expr *pNe; /* Expression (pLeft != pRight) */
Expr *pLeft; /* Value from parent table row */
Expr *pRight; /* Column ref to child table */
pLeft = sqlite3Expr(db, TK_REGISTER, 0);
@ -556,8 +558,8 @@ static void fkScanChildren(
pRight->iTable = pSrc->a[0].iCursor;
pRight->iColumn = -1;
}
pEq = sqlite3PExpr(pParse, TK_NE, pLeft, pRight, 0);
pWhere = sqlite3ExprAnd(db, pWhere, pEq);
pNe = sqlite3PExpr(pParse, TK_NE, pLeft, pRight, 0);
pWhere = sqlite3ExprAnd(db, pWhere, pNe);
}
/* Resolve the references in the WHERE clause. */
@ -587,8 +589,8 @@ static void fkScanChildren(
}
/*
** This function returns a pointer to the head of a linked list of FK
** constraints for which table pTab is the parent table. For example,
** This function returns a linked list of FKey objects (connected by
** FKey.pNextTo) holding all children of table pTab. For example,
** given the following schema:
**
** CREATE TABLE t1(a PRIMARY KEY);
@ -890,7 +892,8 @@ void sqlite3FkCheck(
sqlite3DbFree(db, aiFree);
}
/* Loop through all the foreign key constraints that refer to this table */
/* Loop through all the foreign key constraints that refer to this table.
** (the "child" constraints) */
for(pFKey = sqlite3FkReferences(pTab); pFKey; pFKey=pFKey->pNextTo){
Index *pIdx = 0; /* Foreign key index for pFKey */
SrcList *pSrc;
@ -915,9 +918,8 @@ void sqlite3FkCheck(
}
assert( aiCol || pFKey->nCol==1 );
/* Create a SrcList structure containing a single table (the table
** the foreign key that refers to this table is attached to). This
** is required for the sqlite3WhereXXX() interface. */
/* Create a SrcList structure containing the child table. We need the
** child table as a SrcList for sqlite3WhereBegin() */
pSrc = sqlite3SrcListAppend(db, 0, 0, 0);
if( pSrc ){
struct SrcList_item *pItem = pSrc->a;

29
src/sqliteInt.h

@ -1451,26 +1451,35 @@ struct Table {
** );
**
** For foreign key "fk1", the from-table is "ex1" and the to-table is "ex2".
** Equivalent names:
**
** from-table == child-table
** to-table == parent-table
**
** Each REFERENCES clause generates an instance of the following structure
** which is attached to the from-table. The to-table need not exist when
** the from-table is created. The existence of the to-table is not checked.
**
** The list of all parents for child Table X is held at X.pFKey.
**
** A list of all children for a table named Z (which might not even exist)
** is held in Schema.fkeyHash with a hash key of Z.
*/
struct FKey {
Table *pFrom; /* Table containing the REFERENCES clause (aka: Child) */
FKey *pNextFrom; /* Next foreign key in pFrom */
FKey *pNextFrom; /* Next FKey with the same in pFrom. Next parent of pFrom */
char *zTo; /* Name of table that the key points to (aka: Parent) */
FKey *pNextTo; /* Next foreign key on table named zTo */
FKey *pPrevTo; /* Previous foreign key on table named zTo */
FKey *pNextTo; /* Next with the same zTo. Next child of zTo. */
FKey *pPrevTo; /* Previous with the same zTo */
int nCol; /* Number of columns in this key */
/* EV: R-30323-21917 */
u8 isDeferred; /* True if constraint checking is deferred till COMMIT */
u8 aAction[2]; /* ON DELETE and ON UPDATE actions, respectively */
Trigger *apTrigger[2]; /* Triggers for aAction[] actions */
struct sColMap { /* Mapping of columns in pFrom to columns in zTo */
int iFrom; /* Index of column in pFrom */
char *zCol; /* Name of column in zTo. If 0 use PRIMARY KEY */
} aCol[1]; /* One entry for each of nCol column s */
u8 isDeferred; /* True if constraint checking is deferred till COMMIT */
u8 aAction[2]; /* ON DELETE and ON UPDATE actions, respectively */
Trigger *apTrigger[2];/* Triggers for aAction[] actions */
struct sColMap { /* Mapping of columns in pFrom to columns in zTo */
int iFrom; /* Index of column in pFrom */
char *zCol; /* Name of column in zTo. If NULL use PRIMARY KEY */
} aCol[1]; /* One entry for each of nCol columns */
};
/*