[tarantool-patches] Re: [PATCH 1/4] sql: remove unused opcodes from OP_[Sorter/Idx][Insert/Replace]

["n.pettik" <korablev@tarantool.org>]

You may not pay attention to ’nitpickings’,
but I should make visibility of reviewing this patch.

> On 4 Apr 2018, at 13:26, Vladislav Shpilevoy <v.shpilevoy@tarantool.org> wrote:
> 
> Hello. See the diff at the end of the letter, and my responses to some of
> your comments.
>>> done in a primary index only. It is enough to pass a register of
>>> a primary index.
>> Nitpicking: not 'a register of a primary index’,
>> but number of cursor opened on this space/index.
> Here you are wrong - it is a register, where tuple data is stored to insert. Cursor id
> argument is not changed. I fixed it in a new commit.

Ok, I have misunderstood you.
Now it is clear that you mentioned another operand.

>> 
>>> +		bool no_foreign_keys =
>>> +			sqlite3FkReferences(pTab) == NULL ||
>>> +			(user_session->sql_flags & SQLITE_ForeignKeys) == 0;
>> AFAIK SQLITE_ForeignKeys flag is always set to be true
>> (since we always use FK). Thus, you can remove this condition check.
> Yes, Foreign Keys source code now is always built, because we have removed OMIT_FOREIGN_KEYS,
> but SQLITE_ForeignKeys is not a #define - it is a flag, that can be set by a user on runtime in its
> session, and allows to skip foreign keys checking. The removal of this flags must be discussed,
> because I think it can be useful.
> 
> In any case, talking about the patch, I found a way to remove this code completely. See diff below.

Ok, looks pretty good.

> 
> 
> diff --git a/src/box/sql/analyze.c b/src/box/sql/analyze.c
> index c5dcedd3e..4eae896ab 100644
> --- a/src/box/sql/analyze.c
> +++ b/src/box/sql/analyze.c
> @@ -1050,7 +1050,6 @@ analyzeOneTable(Parse * pParse,	/* Parser context */
> 		sqlite3VdbeAddOp4(v, OP_MakeRecord, regTabname, 3, regTemp,
> 				  "BBB", 0);
> 		sqlite3VdbeAddOp2(v, OP_IdxInsert, iStatCur, regTemp);
> -		sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
>  		/* Add the entries to the stat4 table. */
> diff --git a/src/box/sql/build.c b/src/box/sql/build.c
> index 5e3ed0f39..5c3cac881 100644
> --- a/src/box/sql/build.c
> +++ b/src/box/sql/build.c
> @@ -2659,7 +2659,6 @@ sqlite3RefillIndex(Parse * pParse, Index * pIndex, int memRootPage)
> 	sqlite3VdbeAddOp3(v, OP_SorterData, iSorter, regRecord, iIdx);
> 	sqlite3VdbeAddOp3(v, OP_Last, iIdx, 0, -1);
> 	sqlite3VdbeAddOp2(v, OP_IdxInsert, iIdx, regRecord);
> -	sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
> 	sqlite3ReleaseTempReg(pParse, regRecord);
> 	sqlite3VdbeAddOp2(v, OP_SorterNext, iSorter, addr2);
> 	VdbeCoverage(v);
> diff --git a/src/box/sql/insert.c b/src/box/sql/insert.c
> index c7fe92cd6..c76910e5b 100644
> --- a/src/box/sql/insert.c
> +++ b/src/box/sql/insert.c
> @@ -851,23 +851,7 @@ sqlite3Insert(Parse * pParse,	/* Parser context */
> 						ipkColumn >= 0, onError,
> 						endOfLoop, &isReplace, 0);
> 		sqlite3FkCheck(pParse, pTab, 0, regIns, 0);
> -
> -		/* Set the OPFLAG_USESEEKRESULT flag if either (a) there are no REPLACE
> -		 * constraints or (b) there are no triggers and this table is not a
> -		 * parent table in a foreign key constraint. It is safe to set the
> -		 * flag in the second case as if any REPLACE constraint is hit, an
> -		 * OP_Delete or OP_IdxDelete instruction will be executed on each
> -		 * cursor that is disturbed. And these instructions both clear the
> -		 * VdbeCursor.seekResult variable, disabling the OPFLAG_USESEEKRESULT
> -		 * functionality.
> -		 */
> -		bool no_foreign_keys =
> -			sqlite3FkReferences(pTab) == NULL ||
> -			(user_session->sql_flags & SQLITE_ForeignKeys) == 0;
> -		bool use_seek = isReplace == 0 ||
> -				(pTrigger == NULL && no_foreign_keys);
> -		vdbe_emit_complete_insertion(v, iIdxCur, aRegIdx[0], use_seek,
> -					     onError);
> +		vdbe_emit_insertion_completion(v, iIdxCur, aRegIdx[0], onError);
> 	}
>  	/* Update the count of rows that are inserted
> @@ -1491,20 +1475,16 @@ sqlite3GenerateConstraintChecks(Parse * pParse,		/* The parser context */
> }
>  void
> -vdbe_emit_complete_insertion(Vdbe *v, int cursor_id, int tuple_id,
> -			     bool use_seek_result, u8 on_error)
> +vdbe_emit_insertion_completion(Vdbe *v, int cursor_id, int tuple_id, u8 on_error)
> {
> 	assert(v != NULL);
> -	u16 pik_flags = OPFLAG_NCHANGE;
> -	if (use_seek_result)
> -		pik_flags |= OPFLAG_USESEEKRESULT;
> -
> 	int opcode;
> 	if (on_error == ON_CONFLICT_ACTION_REPLACE)
> 		opcode = OP_IdxReplace;
> 	else
> 		opcode = OP_IdxInsert;
> +	u16 pik_flags = OPFLAG_NCHANGE;
> 	if (on_error == ON_CONFLICT_ACTION_IGNORE)
> 		pik_flags |= OPFLAG_OE_IGNORE;
> 	else if (on_error == ON_CONFLICT_ACTION_FAIL)
> @@ -1910,7 +1890,6 @@ xferOptimization(Parse * pParse,	/* Parser context */
> 	}
>  	for (pDestIdx = pDest->pIndex; pDestIdx; pDestIdx = pDestIdx->pNext) {
> -		u8 idxInsFlags = 0;
> 		for (pSrcIdx = pSrc->pIndex; ALWAYS(pSrcIdx);
> 		     pSrcIdx = pSrcIdx->pNext) {
> 			if (xferCompatibleIndex(pDestIdx, pSrcIdx))
> @@ -1927,11 +1906,9 @@ xferOptimization(Parse * pParse,	/* Parser context */
> 		addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iSrc, 0);
> 		VdbeCoverage(v);
> 		sqlite3VdbeAddOp2(v, OP_RowData, iSrc, regData);
> -		if (pDestIdx->idxType == SQLITE_IDXTYPE_PRIMARYKEY) {
> -			idxInsFlags |= OPFLAG_NCHANGE;
> -		}
> 		sqlite3VdbeAddOp2(v, OP_IdxInsert, iDest, regData);
> -		sqlite3VdbeChangeP5(v, idxInsFlags | OPFLAG_APPEND);
> +		if (pDestIdx->idxType == SQLITE_IDXTYPE_PRIMARYKEY)

Nitpicking: you can use IsPimaryKeyIndex() macros for this purpose.

> +			sqlite3VdbeChangeP5(v, OPFLAG_NCHANGE);
> 		sqlite3VdbeAddOp2(v, OP_Next, iSrc, addr1 + 1);
> 		VdbeCoverage(v);
> 		sqlite3VdbeJumpHere(v, addr1);
> diff --git a/src/box/sql/select.c b/src/box/sql/select.c
> index 95bd7d656..9e64b434e 100644
> --- a/src/box/sql/select.c
> +++ b/src/box/sql/select.c
> @@ -1151,7 +1151,6 @@ selectInnerLoop(Parse * pParse,		/* The parser context */
> 			if (eDest == SRT_DistQueue) {
> 				sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm + 1,
> 						  r3);
> -				sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
> 			}
> 			for (i = 0; i < nKey; i++) {
> 				sqlite3VdbeAddOp2(v, OP_SCopy,
> diff --git a/src/box/sql/sqliteInt.h b/src/box/sql/sqliteInt.h
> index e786cf842..7c0a214b5 100644
> --- a/src/box/sql/sqliteInt.h
> +++ b/src/box/sql/sqliteInt.h
> @@ -3039,8 +3039,6 @@ struct Parse {
> 				     /* Also used in P2 (not P5) of OP_Delete */
> #define OPFLAG_EPHEM         0x01	/* OP_Column: Ephemeral output is ok */
> #define OPFLAG_ISUPDATE      0x04	/* This OP_Insert is an sql UPDATE */
> -#define OPFLAG_APPEND        0x08	/* This is likely to be an append */
> -#define OPFLAG_USESEEKRESULT 0x10	/* Try to avoid a seek in BtreeInsert() */
> #define OPFLAG_OE_IGNORE    0x200	/* OP_IdxInsert: Ignore flag */
> #define OPFLAG_OE_FAIL      0x400	/* OP_IdxInsert: Fail flag */
> #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
> @@ -3722,13 +3720,11 @@ void sqlite3GenerateConstraintChecks(Parse *, Table *, int *, int, int, int,
>  * @param v Virtual database engine.
>  * @param cursor_id Primary index cursor.
>  * @param tuple_id Register with data to insert.
> - * @param use_seek_result True to set the USESEEKRESULT flag on
> - *        OP_[Idx]Insert.
>  * @param on_error Error action on failed insert/replace.
>  */
> void
> -vdbe_emit_complete_insertion(Vdbe *v, int cursor_id, int tuple_id,
> -			     bool use_seek_result, u8 on_error);
> +vdbe_emit_insertion_completion(Vdbe *v, int cursor_id, int tuple_id,
> +			       u8 on_error);
>  int sqlite3OpenTableAndIndices(Parse *, Table *, int, u8, int, u8 *, int *,
> 			       int *, u8, u8);
> diff --git a/src/box/sql/update.c b/src/box/sql/update.c
> index 859189a7e..98e696ddf 100644
> --- a/src/box/sql/update.c
> +++ b/src/box/sql/update.c
> @@ -615,8 +615,7 @@ sqlite3Update(Parse * pParse,		/* The parser context */
> 		}
>  		/* Insert the new index entries and the new record. */
> -		vdbe_emit_complete_insertion(v, iIdxCur, aRegIdx[0], false,
> -					     onError);
> +		vdbe_emit_insertion_completion(v, iIdxCur, aRegIdx[0], onError);
>  		/* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
> 		 * handle rows (possibly in other tables) that refer via a foreign key
> diff --git a/src/box/sql/vdbe.c b/src/box/sql/vdbe.c
> index bf8a27709..5a56727da 100644
> --- a/src/box/sql/vdbe.c
> +++ b/src/box/sql/vdbe.c
> @@ -4321,24 +4321,11 @@ case OP_Next:          /* jump */
> /* Opcode: IdxInsert P1 P2 * * P5
>  * Synopsis: key=r[P2]
>  *
> - * Register P2 holds an SQL index key made using the
> - * MakeRecord instructions.  This opcode writes that key
> - * into the index P1.  Data for the entry is nil.
> - *
> - * If P5 has the OPFLAG_APPEND bit set, that is a hint to the b-tree layer
> - * that this insert is likely to be an append.
> - *
> - * If P5 has the OPFLAG_NCHANGE bit set, then the change counter is
> - * incremented by this instruction.  If the OPFLAG_NCHANGE bit is clear,
> - * then the change counter is unchanged.
> - *
> - * If the OPFLAG_USESEEKRESULT flag of P5 is set, the implementation might
> - * run faster by avoiding an unnecessary seek on cursor P1.  However,
> - * the OPFLAG_USESEEKRESULT flag must only be set if there have been no prior
> - * seeks on the cursor or if the most recent seek used a key equivalent
> - * to P2.
> - *
> - * This instruction only works for indices.
> + * @param P1 Index of a space cursor.
> + * @param P2 Index of a register with MessagePack data to insert.
> + * @param P5 Flags. If P5 contains OPFLAG_NCHANGE, then VDBE
> + *        accounts the change in a case of successful insertion in
> + *        nChange counter.
>  */
> /* Opcode: IdxReplace P1 P2 * * P5
>  * Synopsis: key=r[P2]
> diff --git a/src/box/sql/where.c b/src/box/sql/where.c
> index 79de5d69a..c51bd7455 100644
> --- a/src/box/sql/where.c
> +++ b/src/box/sql/where.c
> @@ -844,7 +844,6 @@ constructAutomaticIndex(Parse * pParse,			/* The parsing context */
> 	    sqlite3GenerateIndexKey(pParse, pIdx, pLevel->iTabCur, regRecord, 0,
> 				    0, 0);
> 	sqlite3VdbeAddOp2(v, OP_IdxInsert, pLevel->iIdxCur, regRecord);
> -	sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
> 	if (pPartial)
> 		sqlite3VdbeResolveLabel(v, iContinue);
> 	if (pTabItem->fg.viaCoroutine) {
> diff --git a/src/box/sql/wherecode.c b/src/box/sql/wherecode.c
> index a3c51eef4..aaffa7c1c 100644
> --- a/src/box/sql/wherecode.c
> +++ b/src/box/sql/wherecode.c
> @@ -1766,10 +1766,6 @@ sqlite3WhereCodeOneLoopStart(WhereInfo * pWInfo,	/* Complete information about t
> 							sqlite3VdbeAddOp2
> 								(v, OP_IdxInsert,
> 								 regRowset, regPk);
> -							if (iSet)
> -								sqlite3VdbeChangeP5
> -									(v,
> -									 OPFLAG_USESEEKRESULT);
> 						}
>  						/* Release the array of temp registers */
> 
> 
>