Horton

Re: tablecmds.c/MergeAttributes() cleanup

Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>

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From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
To: Alexander Lakhin <exclusion@gmail.com>
Cc: Peter Eisentraut <peter@eisentraut.org>, pgsql-hackers <pgsql-hackers@postgresql.org>, Alvaro Herrera <alvherre@alvh.no-ip.org>
Date: 2024-01-30T06:22:43Z
Lists: pgsql-hackers 
Hi Alexander,

On Sun, Jan 28, 2024 at 1:30 PM Alexander Lakhin <exclusion@gmail.com> wrote:
>
> Hello Peter,
>
> 26.01.2024 16:42, Peter Eisentraut wrote:
> >
> > I have committed all this.  These are great improvements.
> >
>
> Please look at the segmentation fault triggered by the following query since
> 4d969b2f8:
> CREATE TABLE t1(a text COMPRESSION pglz);
> CREATE TABLE t2(a text);
> CREATE TABLE t3() INHERITS(t1, t2);
> NOTICE:  merging multiple inherited definitions of column "a"
> server closed the connection unexpectedly
>          This probably means the server terminated abnormally
>          before or while processing the request.
>
> Core was generated by `postgres: law regression [local] CREATE TABLE                                 '.
> Program terminated with signal SIGSEGV, Segmentation fault.
>
> (gdb) bt
> #0  __strcmp_avx2 () at ../sysdeps/x86_64/multiarch/strcmp-avx2.S:116
> #1  0x00005606fbcc9d52 in MergeAttributes (columns=0x0, supers=supers@entry=0x5606fe293d30, relpersistence=112 'p',
> is_partition=false, supconstr=supconstr@entry=0x7fff4046d410, supnotnulls=supnotnulls@entry=0x7fff4046d418)
>      at tablecmds.c:2811
> #2  0x00005606fbccd764 in DefineRelation (stmt=stmt@entry=0x5606fe26a130, relkind=relkind@entry=114 'r', ownerId=10,
> ownerId@entry=0, typaddress=typaddress@entry=0x0,
>      queryString=queryString@entry=0x5606fe2695c0 "CREATE TABLE t3() INHERITS(t1, t2);") at tablecmds.c:885

This bug existed even before the refactoring.Happens because strcmp()
is called on NULL input (t2's compression is NULL). I already have a
fix for this and will be posting it in [1].

[1] https://www.postgresql.org/message-id/flat/24656cec-d6ef-4d15-8b5b-e8dfc9c833a7%40eisentraut.org

-- 
Best Wishes,
Ashutosh Bapat

Commits

  1. Fix segmentation fault in MergeInheritedAttribute()

  2. Improve compression and storage support with inheritance

  3. Split some code out from MergeAttributes()

  4. MergeAttributes code deduplication

  5. Add a const decoration

  6. MergeAttributes: convert pg_attribute back to ColumnDef before comparing

  7. Refactor ATExecAddColumn() to use BuildDescForRelation()

  8. Move BuildDescForRelation() from tupdesc.c to tablecmds.c

  9. Push attcompression and attstorage handling into BuildDescForRelation()

  10. Push attidentity and attgenerated handling into BuildDescForRelation()

  11. Add TupleDescGetDefault()

  12. MergeAttributes() and related variable renaming

  13. Clean up MergeCheckConstraint()

  14. Clean up MergeAttributesIntoExisting()

  15. Remove useless if condition

  16. Make more use of makeColumnDef()

  17. Add some const decorations

  18. Remove ancient special case code for dropping oid columns

  19. Remove ancient special case code for adding oid columns

  20. Remove obsolete comment about OID support