database/postgres
database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-05 23:56:58 +03:00
Code

doc: clarify text around MVCC example query

Browse Source 
Reported-by: marlene.brandstaetter@cargonet.software

Discussion: https://postgr.es/m/167765529052.987840.12345375075704447735@wrigleys.postgresql.org

Backpatch-through: master
This commit is contained in:
Bruce Momjian 2024-11-01 16:38:16 -04:00
parent 4a9effe45e
commit 2fa255ce9b
1 changed files with 4 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
doc/src/sgml/mvcc.sgml
View File

@ -417,8 +417,8 @@
does not see effects of those commands on other rows in the database. does not see effects of those commands on other rows in the database.
This behavior makes Read Committed mode unsuitable for commands that This behavior makes Read Committed mode unsuitable for commands that
involve complex search conditions; however, it is just right for simpler involve complex search conditions; however, it is just right for simpler
cases. For example, consider updating bank balances with transactions cases. For example, consider transferring $100 from one account
like: to another:
<screen> <screen>
BEGIN; BEGIN;
@ -427,8 +427,8 @@ UPDATE accounts SET balance = balance - 100.00 WHERE acctnum = 7534;
COMMIT; COMMIT;
</screen> </screen>
If two such transactions concurrently try to change the balance of account If another transactions concurrently tries to change the balance of account
12345, we clearly want the second transaction to start with the updated 7534, we clearly want the second statement to start with the updated
version of the account's row. Because each command is affecting only a version of the account's row. Because each command is affecting only a
predetermined row, letting it see the updated version of the row does predetermined row, letting it see the updated version of the row does
not create any troublesome inconsistency. not create any troublesome inconsistency.