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Tighten coding of inner loops in nocachegetattr ...

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seems to have improved speed of routine by 5% or so ...
This commit is contained in:
Tom Lane 1999-01-24 22:53:25 +00:00
parent 18577547d4
commit 49b6be244c
1 changed files with 33 additions and 41 deletions
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72
src/backend/access/common/heaptuple.c
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@ -8,7 +8,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/common/heaptuple.c,v 1.46 1998/11/27 19:51:27 vadim Exp $ * $Header: /cvsroot/pgsql/src/backend/access/common/heaptuple.c,v 1.47 1999/01/24 22:53:25 tgl Exp $
* *
* NOTES * NOTES
* The old interface functions have been converted to macros * The old interface functions have been converted to macros
@ -311,13 +311,13 @@ heap_getsysattr(HeapTuple tup, Buffer b, int attnum)
* *
* This caches attribute offsets in the attribute descriptor. * This caches attribute offsets in the attribute descriptor.
* *
* an alternate way to speed things up would be to cache offsets * An alternate way to speed things up would be to cache offsets
* with the tuple, but that seems more difficult unless you take * with the tuple, but that seems more difficult unless you take
* the storage hit of actually putting those offsets into the * the storage hit of actually putting those offsets into the
* tuple you send to disk. Yuck. * tuple you send to disk. Yuck.
* *
* This scheme will be slightly slower than that, but should * This scheme will be slightly slower than that, but should
* preform well for queries which hit large #'s of tuples. After * perform well for queries which hit large #'s of tuples. After
* you cache the offsets once, examining all the other tuples using * you cache the offsets once, examining all the other tuples using
* the same attribute descriptor will go much quicker. -cim 5/4/91 * the same attribute descriptor will go much quicker. -cim 5/4/91
* ---------------- * ----------------
@ -331,8 +331,8 @@ nocachegetattr(HeapTuple tuple,
char *tp; /* ptr to att in tuple */ char *tp; /* ptr to att in tuple */
HeapTupleHeader tup = tuple->t_data; HeapTupleHeader tup = tuple->t_data;
bits8 *bp = tup->t_bits; /* ptr to att in tuple */ bits8 *bp = tup->t_bits; /* ptr to att in tuple */
int slow; /* do we have to walk nulls? */
Form_pg_attribute *att = tupleDesc->attrs; Form_pg_attribute *att = tupleDesc->attrs;
int slow = 0; /* do we have to walk nulls? */
#if IN_MACRO #if IN_MACRO
@ -343,6 +343,8 @@ nocachegetattr(HeapTuple tuple,
*isnull = false; *isnull = false;
#endif #endif
attnum--;
/* ---------------- /* ----------------
* Three cases: * Three cases:
* *
@ -354,8 +356,6 @@ nocachegetattr(HeapTuple tuple,
if (HeapTupleNoNulls(tuple)) if (HeapTupleNoNulls(tuple))
{ {
attnum--;
#if IN_MACRO #if IN_MACRO
/* This is handled in the macro */ /* This is handled in the macro */
if (att[attnum]->attcacheoff != -1) if (att[attnum]->attcacheoff != -1)
@ -373,20 +373,13 @@ nocachegetattr(HeapTuple tuple,
return (Datum) fetchatt(&(att[0]), (char *) tup + tup->t_hoff); return (Datum) fetchatt(&(att[0]), (char *) tup + tup->t_hoff);
} }
#endif #endif
slow = 0;
} }
else else
{ {
/* /*
* there's a null somewhere in the tuple * there's a null somewhere in the tuple
*/ */
tp = (char *) tup + tup->t_hoff;
slow = 0;
attnum--;
/* ---------------- /* ----------------
* check to see if desired att is null * check to see if desired att is null
* ---------------- * ----------------
@ -403,34 +396,27 @@ nocachegetattr(HeapTuple tuple,
#endif #endif
/* ---------------- /* ----------------
* Now check to see if any preceeding bits are null... * Now check to see if any preceding bits are null...
* ---------------- * ----------------
*/ */
{ {
int i = 0; /* current offset in bp */ int byte = attnum >> 3;
int mask; /* bit in byte we're looking at */ int finalbit = attnum & 0x07;
char n; /* current byte in bp */
int byte,
finalbit;
byte = attnum >> 3; /* check for nulls "before" final bit of last byte */
finalbit = attnum & 0x07; if ((~ bp[byte]) & ((1 << finalbit) - 1))
for (; i <= byte && !slow; i++)
{
n = bp[i];
if (i < byte)
{
/* check for nulls in any "earlier" bytes */
if ((~n) != 0)
slow = 1; slow = 1;
}
else else
{ {
/* check for nulls "before" final bit of last byte */ /* check for nulls in any "earlier" bytes */
mask = (1 << finalbit) - 1; int i;
if ((~n) & mask) for (i = 0; i < byte; i++)
{
if (bp[i] != 0xFF)
{
slow = 1; slow = 1;
break;
}
} }
} }
} }
@ -449,24 +435,29 @@ nocachegetattr(HeapTuple tuple,
tp + att[attnum]->attcacheoff); tp + att[attnum]->attcacheoff);
} }
else if (attnum == 0) else if (attnum == 0)
return (Datum) fetchatt(&(att[0]), (char *) tp); return (Datum) fetchatt(&(att[0]), tp);
else if (!HeapTupleAllFixed(tuple)) else if (!HeapTupleAllFixed(tuple))
{ {
int j = 0; int j;
/* /*
* In for(), we make this <= and not < because we want to test * In for(), we make this <= and not < because we want to test
* if we can go past it in initializing offsets. * if we can go past it in initializing offsets.
*/ */
for (j = 0; j <= attnum && !slow; j++) for (j = 0; j <= attnum; j++)
{
if (att[j]->attlen < 1 && !VARLENA_FIXED_SIZE(att[j])) if (att[j]->attlen < 1 && !VARLENA_FIXED_SIZE(att[j]))
{
slow = 1; slow = 1;
break;
}
}
} }
} }
/* /*
* if slow is zero, and we got here, we know that we have a tuple with * If slow is zero, and we got here, we know that we have a tuple with
* no nulls. We also have to initialize the remainder of the * no nulls or varlenas before the target attribute.
* If possible, we also want to initialize the remainder of the
* attribute cached offset values. * attribute cached offset values.
*/ */
if (!slow) if (!slow)
@ -550,7 +541,8 @@ nocachegetattr(HeapTuple tuple,
off = att_addlength(off, att[i]->attlen, tp + off); off = att_addlength(off, att[i]->attlen, tp + off);
if (att[i]->attlen == -1 && !VARLENA_FIXED_SIZE(att[i])) if (usecache &&
att[i]->attlen == -1 && !VARLENA_FIXED_SIZE(att[i]))
usecache = false; usecache = false;
} }