database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-24 00:23:06 +03:00
Code Activity

Standardize ItemIdData terminology.

Browse Source 
The term "item pointer" should not be used to refer to ItemIdData
variables, since that is needlessly ambiguous.  Only
ItemPointerData/ItemPointer variables should be called item pointers.

To fix, establish the convention that ItemIdData variables should always
be referred to either as "item identifiers" or "line pointers".  The
term "item identifier" already predominates in docs and translatable
messages, and so should be the preferred alternative there.

Discussion: https://postgr.es/m/CAH2-Wz=c=MZQjUzde3o9+2PLAPuHTpVZPPdYxN=E4ndQ2--8ew@mail.gmail.com
This commit is contained in:
Peter Geoghegan
2019-05-13 15:53:39 -07:00
parent 08ca9d7fec
commit ae7291acbc
14 changed files with 52 additions and 73 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
src/include/storage/bufpage.h
View File

@@ -53,14 +53,18 @@
*
* NOTES:
*
* linp1..N form an ItemId array. ItemPointers point into this array
* rather than pointing directly to a tuple. Note that OffsetNumbers
* linp1..N form an ItemId (line pointer) array. ItemPointers point
* to a physical block number and a logical offset (line pointer
* number) within that block/page. Note that OffsetNumbers
* conventionally start at 1, not 0.
*
* tuple1..N are added "backwards" on the page. because a tuple's
* ItemPointer points to its ItemId entry rather than its actual
* tuple1..N are added "backwards" on the page. Since an ItemPointer
* offset is used to access an ItemId entry rather than an actual
* byte-offset position, tuples can be physically shuffled on a page
* whenever the need arises.
* whenever the need arises. This indirection also keeps crash recovery
* relatively simple, because the low-level details of page space
* management can be controlled by standard buffer page code during
* logging, and during recovery.
*
* AM-generic per-page information is kept in PageHeaderData.
*
@@ -233,7 +237,7 @@ typedef PageHeaderData *PageHeader;
/*
* PageGetContents
* To be used in case the page does not contain item pointers.
* To be used in cases where the page does not contain line pointers.
*
* Note: prior to 8.3 this was not guaranteed to yield a MAXALIGN'd result.
* Now it is. Beware of old code that might think the offset to the contents