Horton

Re: POC: converting Lists into arrays

Petr Jelinek <petr@2ndquadrant.com>

View thread View on postgr.es
From: Petr Jelinek <petr@2ndquadrant.com>
To: Andres Freund <andres@anarazel.de>, Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2019-07-31T23:17:37Z
Lists: pgsql-hackers 
On 01/08/2019 01:04, Andres Freund wrote:
> Hi,
> 
> On 2019-07-31 16:00:47 -0700, Andres Freund wrote:
>> On 2019-07-31 15:57:56 -0700, Andres Freund wrote:
>>> I also wonder if a foreach version that includes the typical
>>> (Type *) var = (Type *) lfirst(lc);
>>> or
>>> (Type *) var = castNode(Type, lfirst(lc));
>>> or
>>> OpExpr	   *hclause = lfirst_node(OpExpr, lc);
>>>
>>> would make it nicer to use lists.
>>>
>>> foreach_node_in(Type, name, list) could mean something like
>>>
>>> foreach(ListCell *name##_cell, list)
>>> {
>>>      Type* name = lfirst_node(Type, name##_cell);
>>> }
>>
>> s/lfirst/linitial/ of course. Was looking at code that also used
>> lfirst...
> 
> Bullshit, of course.
> 
> /me performs a tactical withdrawal into his brown paper bag.
> 
> 
>> Reminds me that one advantage of macros like the second one would also
>> be to reduce the use of the confusingly named linitial*(), helping newer
>> hackers.
> 
> But that point just had two consecutive embarassing demonstrations...
> 

Yeah, pg_list.h is one file I never close.

-- 
Petr Jelinek
2ndQuadrant - PostgreSQL Solutions for the Enterprise
https://www.2ndQuadrant.com/

Commits

  1. Remove EState.es_range_table_array.

  2. Rationalize use of list_concat + list_copy combinations.

  3. Cosmetic improvements in setup of planner's per-RTE arrays.

  4. Make better use of the new List implementation in a couple of places

  5. Fix sepgsql test results for commit d97b714a2.

  6. Avoid using lcons and list_delete_first where it's easy to do so.

  7. Remove lappend_cell...() family of List functions.

  8. Clean up some ad-hoc code for sorting and de-duplicating Lists.

  9. Redesign the API for list sorting (list_qsort becomes list_sort).

  10. Remove dead code.

  11. Represent Lists as expansible arrays, not chains of cons-cells.

  12. Standardize some more loops that chase down parallel lists.

  13. Reimplement the linked list data structure used throughout the backend.