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Improvements to comments. Minor changes to code in the hot path of

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OP_Column - with the hope of get a few cycles of performance improvement.

FossilOrigin-Name: ca093103437f141caa3eb11539c6eb7b4dd65175
This commit is contained in:
drh
2012-03-28 13:41:10 +00:00
parent 3c888b7d1b
commit dda5c08bf6
3 changed files with 20 additions and 19 deletions
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25
src/vdbe.c
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@@ -2128,10 +2128,10 @@ case OP_NotNull: { /* same as TK_NOTNULL, jump, in1 */
** The first OP_Column against a pseudo-table after the value of the content
** register has changed should have this bit set.
**
** If the OPFLAG_LENGTHARG bit is set on P5 then the result is guaranteed
** to only be used as the argument of a length() or typeof() function and
** so loading of large blobs and strings can be skipped - all that is necessary
** is that the size and type information be set.
** If the OPFLAG_LENGTHARG and OPFLAG_TYPEOFARG bits are set on P5 when
** the result is guaranteed to only be used as the argument of a length()
** or typeof() function, respectively. The loading of large blobs can be
** skipped for length() and all content loading can be skipped for typeof().
*/
case OP_Column: {
u32 payloadSize; /* Number of bytes in the record */
@@ -2272,7 +2272,7 @@ case OP_Column: {
pC->aRow = 0;
}
}
/* The following assert is true in all cases accept when
/* The following assert is true in all cases except when
** the database file has been corrupted externally.
** assert( zRec!=0 || avail>=payloadSize || avail>=9 ); */
szHdr = getVarint32((u8*)zData, offset);
@@ -2347,11 +2347,11 @@ case OP_Column: {
break;
}
}else{
/* If i is less that nField, then there are less fields in this
/* If i is less that nField, then there are fewer fields in this
** record than SetNumColumns indicated there are columns in the
** table. Set the offset for any extra columns not present in
** the record to 0. This tells code below to store a NULL
** instead of deserializing a value from the record.
** the record to 0. This tells code below to store the default value
** for the column instead of deserializing a value from the record.
*/
aOffset[i] = 0;
}
@@ -2384,12 +2384,13 @@ case OP_Column: {
VdbeMemRelease(pDest);
sqlite3VdbeSerialGet((u8 *)&zRec[aOffset[p2]], aType[p2], pDest);
}else{
len = sqlite3VdbeSerialTypeLen(aType[p2]);
t = aType[p2];
len = sqlite3VdbeSerialTypeLen(t);
if( (pOp->p5 & (OPFLAG_LENGTHARG|OPFLAG_TYPEOFARG))!=0
&& (((t = aType[p2])>=12 && (t&1)==0) || (pOp->p5 & OPFLAG_TYPEOFARG)!=0)
&& ((t>=12 && (t&1)==0) || (pOp->p5 & OPFLAG_TYPEOFARG)!=0)
){
/* Content is irrelevant for the typeof() function and for
** the length(x) function is x is a blob. So we might as well use
** the length(X) function if X is a blob. So we might as well use
** bogus content rather than reading content from disk. NULL works
** for text and blob and whatever is in the payloadSize64 variable
** will work for everything else. */
@@ -2403,7 +2404,7 @@ case OP_Column: {
}
zData = sMem.z;
}
sqlite3VdbeSerialGet((u8*)zData, aType[p2], pDest);
sqlite3VdbeSerialGet((u8*)zData, t, pDest);
}
pDest->enc = encoding;
}else{