| From: | "houzj(dot)fnst(at)fujitsu(dot)com" <houzj(dot)fnst(at)fujitsu(dot)com> |
|---|---|
| To: | pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Questions about CommandIsReadOnly |
| Date: | 2021-03-09 11:54:04 |
| Message-ID: | OS0PR01MB5716E9700E2BA06B05EFE60494929@OS0PR01MB5716.jpnprd01.prod.outlook.com |
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| Lists: | pgsql-hackers |
Hi hackers,
When reading the code, I found that in function CommandIsReadOnly[1], "select for update/share" is defined as "not read only".
[1]-----------------
if (pstmt->rowMarks != NIL)
return false; /* SELECT FOR [KEY] UPDATE/SHARE */
-----------------
And from the comment [2], I think it means we need to CCI for "select for update/share ",
I am not very familiar this, is there some reason that we have to do CCI for "select for update/share " ?
Or Did I misunderstand ?
[2]-----------------
* the query must be *in truth* read-only, because the caller wishes
* not to do CommandCounterIncrement for it.
-----------------
Best regards,
houzj
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