diff options
Diffstat (limited to 'src/sqliteInt.h')
| -rw-r--r-- | src/sqliteInt.h | 70 |
1 files changed, 52 insertions, 18 deletions
diff --git a/src/sqliteInt.h b/src/sqliteInt.h index ebd0f01b2..d1ffce6d8 100644 --- a/src/sqliteInt.h +++ b/src/sqliteInt.h @@ -1335,6 +1335,7 @@ typedef struct Savepoint Savepoint; typedef struct Select Select; typedef struct SQLiteThread SQLiteThread; typedef struct SelectDest SelectDest; +typedef struct Subquery Subquery; typedef struct SrcItem SrcItem; typedef struct SrcList SrcList; typedef struct sqlite3_str StrAccum; /* Internal alias for sqlite3_str */ @@ -3276,6 +3277,16 @@ struct IdList { #define EU4_EXPR 2 /* Uses IdList.a.u4.pExpr -- NOT CURRENTLY USED */ /* +** Details of the implementation of a subquery. +*/ +struct Subquery { + Select *pSelect; /* A SELECT statement used in place of a table name */ + int addrFillSub; /* Address of subroutine to initialize a subquery */ + int regReturn; /* Register holding return address of addrFillSub */ + int regResult; /* Registers holding results of a co-routine */ +}; + +/* ** The SrcItem object represents a single term in the FROM clause of a query. ** The SrcList object is mostly an array of SrcItems. ** @@ -3287,29 +3298,40 @@ struct IdList { ** In the colUsed field, the high-order bit (bit 63) is set if the table ** contains more than 63 columns and the 64-th or later column is used. ** -** Union member validity: +** Aggressive use of "union" helps keep the size of the object small. This +** has been shown to boost performance, in addition to saving memory. +** Access to union elements is gated by the following rules which should +** always be checked, either by an if-statement or by an assert(). ** -** u1.zIndexedBy fg.isIndexedBy && !fg.isTabFunc -** u1.pFuncArg fg.isTabFunc && !fg.isIndexedBy +** Field Only access if this is true +** --------------- ----------------------------------- +** u1.zIndexedBy fg.isIndexedBy +** u1.pFuncArg fg.isTabFunc ** u1.nRow !fg.isTabFunc && !fg.isIndexedBy ** -** u2.pIBIndex fg.isIndexedBy && !fg.isCte -** u2.pCteUse fg.isCte && !fg.isIndexedBy +** u2.pIBIndex fg.isIndexedBy +** u2.pCteUse fg.isCte +** +** u3.pOn !fg.isUsing +** u3.pUsing fg.isUsing +** +** u4.zDatabase !fg.fixedSchema && !fg.isSubquery +** u4.pSchema fg.fixedSchema +** u4.pSubq fg.isSubquery +** +** See also the sqlite3SrcListDelete() routine for assert() statements that +** check invariants on the fields of this object, especially the flags +** inside the fg struct. */ struct SrcItem { - Schema *pSchema; /* Schema to which this item is fixed */ - char *zDatabase; /* Name of database holding this table */ char *zName; /* Name of the table */ char *zAlias; /* The "B" part of a "A AS B" phrase. zName is the "A" */ - Table *pTab; /* An SQL table corresponding to zName */ - Select *pSelect; /* A SELECT statement used in place of a table name */ - int addrFillSub; /* Address of subroutine to manifest a subquery */ - int regReturn; /* Register holding return address of addrFillSub */ - int regResult; /* Registers holding results of a co-routine */ + Table *pSTab; /* Table object for zName. Mnemonic: Srcitem-TABle */ struct { u8 jointype; /* Type of join between this table and the previous */ unsigned notIndexed :1; /* True if there is a NOT INDEXED clause */ unsigned isIndexedBy :1; /* True if there is an INDEXED BY clause */ + unsigned isSubquery :1; /* True if this term is a subquery */ unsigned isTabFunc :1; /* True if table-valued-function syntax */ unsigned isCorrelated :1; /* True if sub-query is correlated */ unsigned isMaterialized:1; /* This is a materialized view */ @@ -3323,12 +3345,10 @@ struct SrcItem { unsigned isSynthUsing :1; /* u3.pUsing is synthesized from NATURAL */ unsigned isNestedFrom :1; /* pSelect is a SF_NestedFrom subquery */ unsigned rowidUsed :1; /* The ROWID of this table is referenced */ + unsigned fixedSchema :1; /* Uses u4.pSchema, not u4.zDatabase */ + unsigned hadSchema :1; /* Had u4.zDatabase before u4.pSchema */ } fg; int iCursor; /* The VDBE cursor number used to access this table */ - union { - Expr *pOn; /* fg.isUsing==0 => The ON clause of a join */ - IdList *pUsing; /* fg.isUsing==1 => The USING clause of a join */ - } u3; Bitmask colUsed; /* Bit N set if column N used. Details above for N>62 */ union { char *zIndexedBy; /* Identifier from "INDEXED BY <zIndex>" clause */ @@ -3339,6 +3359,15 @@ struct SrcItem { Index *pIBIndex; /* Index structure corresponding to u1.zIndexedBy */ CteUse *pCteUse; /* CTE Usage info when fg.isCte is true */ } u2; + union { + Expr *pOn; /* fg.isUsing==0 => The ON clause of a join */ + IdList *pUsing; /* fg.isUsing==1 => The USING clause of a join */ + } u3; + union { + Schema *pSchema; /* Schema to which this item is fixed */ + char *zDatabase; /* Name of database holding this table */ + Subquery *pSubq; /* Description of a subquery */ + } u4; }; /* @@ -3598,8 +3627,10 @@ struct Select { #define SF_UpdateFrom 0x10000000 /* Query originates with UPDATE FROM */ #define SF_Correlated 0x20000000 /* True if references the outer context */ -/* True if S exists and has SF_NestedFrom */ -#define IsNestedFrom(S) ((S)!=0 && ((S)->selFlags&SF_NestedFrom)!=0) +/* True if SrcItem X is a subquery that has SF_NestedFrom */ +#define IsNestedFrom(X) \ + ((X)->fg.isSubquery && \ + ((X)->u4.pSubq->pSelect->selFlags&SF_NestedFrom)!=0) /* ** The results of a SELECT can be distributed in several ways, as defined @@ -4991,6 +5022,9 @@ int sqlite3IdListIndex(IdList*,const char*); SrcList *sqlite3SrcListEnlarge(Parse*, SrcList*, int, int); SrcList *sqlite3SrcListAppendList(Parse *pParse, SrcList *p1, SrcList *p2); SrcList *sqlite3SrcListAppend(Parse*, SrcList*, Token*, Token*); +void sqlite3SubqueryDelete(sqlite3*,Subquery*); +Select *sqlite3SubqueryDetach(sqlite3*,SrcItem*); +int sqlite3SrcItemAttachSubquery(Parse*, SrcItem*, Select*, int); SrcList *sqlite3SrcListAppendFromTerm(Parse*, SrcList*, Token*, Token*, Token*, Select*, OnOrUsing*); void sqlite3SrcListIndexedBy(Parse *, SrcList *, Token *); |