| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | bossartn(at)amazon(dot)com, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, michael(at)paquier(dot)xyz, sulamul(at)gmail(dot)com, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: inefficient loop in StandbyReleaseLockList() |
| Date: | 2021-11-06 22:32:54 |
| Message-ID: | 613307.1636237974@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Andres Freund <andres(at)anarazel(dot)de> writes:
> On 2021-11-06 14:06:12 -0400, Tom Lane wrote:
>> + * Note that this takes time proportional to the length of the list,
>> + * since the remaining entries must be moved.
>> */
>> List *
>> list_delete_first(List *list)
> Perhaps we could point to list_delete_last()? But it's an improvement without
> that too.
Good point. The note at list_delete_last that it's O(1) isn't really
on point --- instead, the text for list_delete_first should be like
+ * Note that this takes time proportional to the length of the list,
+ * since the remaining entries must be moved. Consider reversing the
+ * list order so that you can use list_delete_last() instead. However,
+ * if that causes you to replace lappend() with lcons(), you haven't
+ * improved matters.
regards, tom lane
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