Hi,
I find some independent improvement in this area. In the detoast_attr,
VARATT_IS_EXTERNAL_ONDISK and VARATT_IS_EXTERNAL_INDIRECT are checked
first, and then VARATT_IS_EXTERNAL_EXPANDED is checked. However when
VARATT_IS_EXTERNAL_EXPANDED is true, detoast_external_attr is called
which would check the previous two cases again. The attached patch uses
a more specific code to handle this.
This would not only remove such the double check overhead, but also make
my following patch easier since I don't need to build a
detoast_external_attr_[buffer] function.
'make check-world' passed.
--
Best Regards
Andy Fan
>From 7208142241ac18e44be2ee87e9c83c451032ca95 Mon Sep 17 00:00:00 2001
From: Andy Fan <zhihuifan1...@163.com>
Date: Tue, 29 Oct 2024 14:05:05 +0800
Subject: [PATCH v20241029 1/1] Using more specific code when detoasting an
expanded datum.
In the detoast_attr function, VARATT_IS_EXTERNAL_ONDISK and
VARATT_IS_EXTERNAL_INDIRECT are checked first, and then
VARATT_IS_EXTERNAL_EXPANDED is checked, However it is true,
detoast_external_attr is called which would check the two cases
again. The attached patch uses a more specific code to handle this.
---
src/backend/access/common/detoast.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/src/backend/access/common/detoast.c b/src/backend/access/common/detoast.c
index 3547cdba56..5f191a83b5 100644
--- a/src/backend/access/common/detoast.c
+++ b/src/backend/access/common/detoast.c
@@ -161,9 +161,15 @@ detoast_attr(struct varlena *attr)
/*
* This is an expanded-object pointer --- get flat format
*/
- attr = detoast_external_attr(attr);
- /* flatteners are not allowed to produce compressed/short output */
- Assert(!VARATT_IS_EXTENDED(attr));
+ ExpandedObjectHeader *eoh;
+ Size resultsize;
+ struct varlena *result;
+
+ eoh = DatumGetEOHP(PointerGetDatum(attr));
+ resultsize = EOH_get_flat_size(eoh);
+ result = (struct varlena *) palloc(resultsize);
+ EOH_flatten_into(eoh, (void *) result, resultsize);
+ attr = result;
}
else if (VARATT_IS_COMPRESSED(attr))
{
--
2.45.1
