Re: Multi-Column List Partitioning

Thanks Nitin,

v4 patches applied cleanly and make check is passing now. While testing
further I observed that if multiple values are given for a single
column list partition it is not giving error instead it is changing values
itself. Please find the example below.

postgres=# CREATE TABLE plt1 (a int, b varchar) PARTITION BY LIST(b);
CREATE TABLE
postgres=# CREATE TABLE plt1_p1 PARTITION OF plt1 FOR VALUES IN
(('0001','0001'),('0002','0002'));
CREATE TABLE
postgres=# \d+ plt1;
Partitioned table "public.plt1"
Column | Type | Collation | Nullable | Default | Storage |
Compression | Stats target | Description
--------+-------------------+-----------+----------+---------+----------+-------------+--------------+-------------
a | integer | | | | plain |
| |
b | character varying | | | | extended |
| |
Partition key: LIST (b)
Partitions: plt1_p1 FOR VALUES IN ('(0001,0001)', '(0002,0002)')

I think it should throw an error as the partition by list has only 1 column
but we are giving 2 values.
also if you see \d+ showing plt1_p1 partition value as ‘(0001,0001)’
instead of ('0001','0001').

Thanks & Regards,
Rajkumar Raghuwanshi

On Sun, Oct 3, 2021 at 1:52 AM Nitin Jadhav <nitinjadhavpostgres(at)gmail(dot)com>
wrote:

> > > On PG head + Nitin's v3 patch + Amit's Delta patch. Make check is
> failing with below errors.
> >
> > Thanks Rajkumar for testing.
> >
> > Here's a v2 of the delta patch that should fix both of these test
> > failures. As I mentioned in my last reply, my delta patch fixed what
> > I think were problems in Nitin's v3 patch but were not complete by
> > themselves. Especially, I hadn't bothered to investigate various /*
> > TODO: handle multi-column list partitioning */ sites to deal with my
> > own changes.
>
> Thanks Rajkumar for testing and Thank you Amit for working on v2 of
> the delta patch. Actually I had done the code changes related to
> partition-wise join and I was in the middle of fixing the review
> comments, So I could not share the patch. Anyways thanks for your
> efforts.
>
> > I noticed that multi-column list partitions containing NULLs don't
> > work correctly with partition pruning yet.
> >
> > create table p0 (a int, b text, c bool) partition by list (a, b, c);
> > create table p01 partition of p0 for values in ((1, 1, true), (NULL, 1,
> false));
> > create table p02 partition of p0 for values in ((1, NULL, false));
> > explain select * from p0 where a is null;
> > QUERY PLAN
> > --------------------------------------------------------
> > Seq Scan on p01 p0 (cost=0.00..22.50 rows=6 width=37)
> > Filter: (a IS NULL)
> > (2 rows)
> >
> > In the attached updated version, I've dealt with some of those such
> > that at least the existing cases exercising partition pruning and
> > partition wise joins now pass.
>
> wrt partition pruning, I have checked the output of the above case
> with the v2 version of the delta patch and without that. The output
> remains same. Kindly let me know if I am missing something. But I feel
> the above output is correct as the partition p01 is the only partition
> which contains NULL value for column a, hence it is showing "Seq scan
> on p01" in the output. Kindly correct me if I am wrong. I feel the
> code changes related to 'null_keys' is not required, hence not
> incorporated that in the attached patch.
>
> wrt partition-wise join, I had run the regression test (with new cases
> related to partition-wise join) on v2 of the delta patch and observed
> the crash. Hence I have not incorporated the partition-wise join
> related code from v2 of delta patch to main v4 patch. Instead I have
> added the partition-wise join related code done by me in the attached
> patch. Please share your thoughts and if possible we can improvise the
> code. Rest of the changes looks good to me and I have incorporated
> that in the attached patch.
>
>
> > I guess that may be due to the following newly added code being
> incomplete:
> > Maybe this function needs to return a "bitmapset" of indexes, because
> > multiple partitions can now contain NULL values.
>
> I feel this function is not required at all as we are not separating
> the non null and null partitions now. Removed in the attached patch.
> Also removed the "scan_null' variable from the structure
> "PruneStepResult" and cleaned up the corresponding code blocks.
>
>
> > This function name may be too generic. Given that it is specific to
> > implementing list bound de-duplication, maybe the following signature
> > is more appropriate:
> >
> > static bool
> > checkListBoundDuplicated(List *list_bounds, List *new_bound)
>
> Yes. The function name looks more generic. How about using
> "isListBoundDuplicated()"? I have used this name in the patch. Please
> let me know if that does not look correct.
>
>
> > Also, better if the function comment mentions those parameter names,
> like:
> >
> > "Returns TRUE if the list bound element 'new_bound' is already present
> > in the target list 'list_bounds', FALSE otherwise."
>
> Fixed.
>
>
> > +/*
> > + * transformPartitionListBounds
> > + *
> > + * Converts the expressions of list partition bounds from the raw
> grammar
> > + * representation.
> >
> > A sentence about the result format would be helpful, like:
> >
> > The result is a List of Lists of Const nodes to account for the
> > partition key possibly containing more than one column.
>
> Fixed.
>
>
> > + int i = 0;
> > + int j = 0;
> >
> > Better to initialize such loop counters closer to the loop.
>
> Fixed in all the places.
>
>
> > + colname[i] = (char *) palloc0(NAMEDATALEN * sizeof(char));
> > + colname[i] = get_attname(RelationGetRelid(parent),
> > + key->partattrs[i], false);
> >
> > The palloc in the 1st statement is wasteful, because the 2nd statement
> > overwrites its pointer by the pointer to the string palloc'd by
> > get_attname().
>
> Removed the 1st statement as it is not required.
>
>
> > + ListCell *cell2 = NULL;
> >
> > No need to explicitly initialize the loop variable.
>
> Fixed in all the places.
>
>
> > + RowExpr *rowexpr = NULL;
> > +
> > + if (!IsA(expr, RowExpr))
> > + ereport(ERROR,
> > + (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
> > + errmsg("Invalid list bound specification"),
> > + parser_errposition(pstate, exprLocation((Node
> > *) spec))));
> > +
> > + rowexpr = (RowExpr *) expr;
> >
> > It's okay to assign rowexpr at the top here instead of the dummy
> > NULL-initialization and write the condition as:
> >
> > if (!IsA(rowexpr, RowExpr))
>
> Fixed.
>
>
> > + if (isDuplicate)
> > + continue;
> > +
> > + result = lappend(result, values);
> >
> > I can see you copied this style from the existing code, but how about
> > writing this simply as:
> >
> > if (!isDuplicate)
> > result = lappend(result, values);
>
> This looks good. I have changed in the patch.
>
>
> > -/* One value coming from some (index'th) list partition */
> > +/* One bound of a list partition */
> > typedef struct PartitionListValue
> > {
> > int index;
> > - Datum value;
> > + Datum *values;
> > + bool *isnulls;
> > } PartitionListValue;
> >
> > Given that this is a locally-defined struct, I wonder if it makes
> > sense to rename the struct while we're at it. Call it, say,
> > PartitionListBound?
>
> Yes. PartitionListBound looks more appropriate and it also matches the
> similar structures of the other partition strategies.
>
> > Also, please keep part of the existing comment that says that the
> > bound belongs to index'th partition.
>
> Retained the old comment.
>
>
> > + * partition_bound_accepts_nulls
> > + *
> > + * Returns TRUE if partition bound has NULL value, FALSE otherwise.
> > */
> >
> > I suggest slight rewording, as follows:
> >
> > "Returns TRUE if any of the partition bounds contains a NULL value,
> > FALSE otherwise."
>
> Fixed.
>
>
> > - PartitionListValue *all_values;
> > + PartitionListValue **all_values;
> > ...
> > - all_values = (PartitionListValue *)
> > - palloc(ndatums * sizeof(PartitionListValue));
> > + ndatums = get_list_datum_count(boundspecs, nparts);
> > + all_values = (PartitionListValue **)
> > + palloc(ndatums * sizeof(PartitionListValue *));
> >
> > I don't see the need to redefine all_values's pointer type. No need
> > to palloc PartitionListValue repeatedly for every datum as done
> > further down as follows:
> >
> > + all_values[j] = (PartitionListValue *)
> > palloc(sizeof(PartitionListValue));
> >
> > You do need the following two though:
> >
> > + all_values[j]->values = (Datum *) palloc0(key->partnatts *
> > sizeof(Datum));
> > + all_values[j]->isnulls = (bool *) palloc0(key->partnatts *
> > sizeof(bool));
> >
> > If you change the above the way I suggest, you'd also need to revert
> > the following change:
> >
> > - qsort_arg(all_values, ndatums, sizeof(PartitionListValue),
> > + qsort_arg(all_values, ndatums, sizeof(PartitionListValue *),
> > qsort_partition_list_value_cmp, (void *) key);
> >
> > + int orig_index = all_values[i]->index;
> > + boundinfo->datums[i] = (Datum *) palloc(key->partnatts *
> sizeof(Datum));
> >
> > Missing a newline between these two statements.
>
> Fixed. Made necessary changes to keep the intent of existing code.
>
>
> > @@ -915,7 +949,7 @@ partition_bounds_equal(int partnatts, int16
> > *parttyplen, bool *parttypbyval,
> > if (b1->nindexes != b2->nindexes)
> > return false;
> >
> > - if (b1->null_index != b2->null_index)
> > + if (get_partition_bound_null_index(b1) !=
> > get_partition_bound_null_index(b2))
> >
> > As mentioned in the last message, this bit in partition_bounds_equal()
> > needs to be comparing "bitmapsets" of null bound indexes, that is
> > after fixing get_partition_bound_null_index() as previously mentioned.
>
> As mentioned earlier, removed the functionality of
> get_partition_bound_null_index(), hence the above condition is not
> required and removed.
>
> > But...
> >
> > @@ -988,7 +1022,22 @@ partition_bounds_equal(int partnatts, int16
> > *parttyplen, bool *parttypbyval,
> > * context. datumIsEqual() should be simple enough to be
> > * safe.
> > */
> > - if (!datumIsEqual(b1->datums[i][j], b2->datums[i][j],
> > + if (b1->isnulls)
> > + b1_isnull = b1->isnulls[i][j];
> > + if (b2->isnulls)
> > + b2_isnull = b2->isnulls[i][j];
> > +
> > + /*
> > + * If any of the partition bound has NULL value, then
> check
> > + * equality for the NULL value instead of comparing the
> datums
> > + * as it does not contain valid value in case of NULL.
> > + */
> > + if (b1_isnull || b2_isnull)
> > + {
> > + if (b1_isnull != b2_isnull)
> > + return false;
> > + }
> >
> > ...if you have this in the main loop, I don't think we need the above
> > code stanza which appears to implement a short-cut for this long-form
> > logic.
>
> Yes. May be we could have ignored the above code stanza if we would
> have comparing the null indexes using get_partition_bound_null_index()
> in the beginning of the function. But hence we are not separating the
> non null partitions and null partitions, I would like to keep the
> logic in the inner loop as we are doing it for non null bound values
> in the above code stanza, just to give a feel that null bound values
> are also handled the same way as non null values. Please correct me if
> I am wrong.
>
>
> > + (key->strategy != PARTITION_STRATEGY_LIST ||
> > + !src->isnulls[i][j]))
> >
> > I think it's better to write this condition as follows just like the
> > accompanying condition involving src->kind:
> >
> > (src->nulls == NULL || !src->isnulls[i][j])
>
> Fixed.
>
>
> > In check_new_partition_bound():
> >
> > + Datum *values = (Datum *)
> > palloc0(key->partnatts * sizeof(Datum));
> > + bool *isnulls = (bool *)
> > palloc0(key->partnatts * sizeof(bool));
> >
> > Doesn't seem like a bad idea to declare these as:
> >
> > Datum values[PARTITION_MAX_KEYS];
> > bool isnulls[PARTITION_MAX_KEYS];
>
> Thanks for the suggestion. I have changed as above.
>
> > I looked at get_qual_for_list_multi_column() and immediately thought
> > that it may be a bad idea. I think it's better to integrate the logic
> > for multi-column case into the existing function even if that makes
> > the function appear more complex. Having two functions with the same
> > goal and mostly the same code is not a good idea mainly because it
> > becomes a maintenance burden.
>
> Actually I had written a separate function because of the complexity.
> Now I have understood that since the objective is same, it should be
> done in a single function irrespective of complexity.
>
> > I have attempted a rewrite such that get_qual_for_list() now handles
> > both the single-column and multi-column cases. Changes included in
> > the delta patch. The patch updates some outputs of the newly added
> > tests for multi-column list partitions, because the new code emits the
> > IS NOT NULL tests a bit differently than
> > get_qual_for_list_mutli_column() would. Notably, the old approach
> > would emit IS NOT NULL for every non-NULL datum matched to a given
> > column, not just once for the column. However, the patch makes a few
> > other tests fail, mainly because I had to fix
> > partition_bound_accepts_nulls() to handle the multi-column case,
> > though didn't bother to update all callers of it to also handle the
> > multi-column case correctly. I guess that's a TODO you're going to
> > deal with at some point anyway. :)
>
> Thank you very much for your efforts. The changes looks good to me and
> I have incorporated these changes in the attached patch.
>
> I have completed the coding for all the TODOs and hence removed in the
> patch. The naming conventions used for function/variable names varies
> across the files. Some places it is like 'namesLikeThis' and in some
> place it is like 'names_like_this'. I have used the naming conventions
> based on the surrounding styles used. I am happy to change those if
> required.
>
> I have verified 'make check' with the attached patch and it is working
> fine.
>
>
> Thanks & Regards,
> Nitin Jadhav
>
>
> On Mon, Sep 13, 2021 at 3:47 PM Rajkumar Raghuwanshi
> <rajkumar(dot)raghuwanshi(at)enterprisedb(dot)com> wrote:
> >
> > On PG head + Nitin's v3 patch + Amit's Delta patch. Make check is
> failing with below errors.
> >
> > --inherit.sql is failing with error :"ERROR: negative bitmapset member
> not allowed"
> > update mlparted_tab mlp set c = 'xxx'
> > from
> > (select a from some_tab union all select a+1 from some_tab) ss (a)
> > where (mlp.a = ss.a and mlp.b = 'b') or mlp.a = 3;
> > ERROR: negative bitmapset member not allowed
> >
> > --partition_join.sql is crashing with enable_partitionwise_join set to
> true.
> > CREATE TABLE plt1_adv (a int, b int, c text) PARTITION BY LIST (c);
> > CREATE TABLE plt1_adv_p1 PARTITION OF plt1_adv FOR VALUES IN ('0001',
> '0003');
> > CREATE TABLE plt1_adv_p2 PARTITION OF plt1_adv FOR VALUES IN ('0004',
> '0006');
> > CREATE TABLE plt1_adv_p3 PARTITION OF plt1_adv FOR VALUES IN ('0008',
> '0009');
> > INSERT INTO plt1_adv SELECT i, i, to_char(i % 10, 'FM0000') FROM
> generate_series(1, 299) i WHERE i % 10 IN (1, 3, 4, 6, 8, 9);
> > ANALYZE plt1_adv;
> > CREATE TABLE plt2_adv (a int, b int, c text) PARTITION BY LIST (c);
> > CREATE TABLE plt2_adv_p1 PARTITION OF plt2_adv FOR VALUES IN ('0002',
> '0003');
> > CREATE TABLE plt2_adv_p2 PARTITION OF plt2_adv FOR VALUES IN ('0004',
> '0006');
> > CREATE TABLE plt2_adv_p3 PARTITION OF plt2_adv FOR VALUES IN ('0007',
> '0009');
> > INSERT INTO plt2_adv SELECT i, i, to_char(i % 10, 'FM0000') FROM
> generate_series(1, 299) i WHERE i % 10 IN (2, 3, 4, 6, 7, 9);
> > ANALYZE plt2_adv;
> > -- inner join
> > EXPLAIN (COSTS OFF)
> > SELECT t1.a, t1.c, t2.a, t2.c FROM plt1_adv t1 INNER JOIN plt2_adv t2 ON
> (t1.a = t2.a AND t1.c = t2.c) WHERE t1.b < 10 ORDER BY t1.a;
> > server closed the connection unexpectedly
> > This probably means the server terminated abnormally
> > before or while processing the request.
> > connection to server was lost
> >
> >
> > --stack-trace
> > Core was generated by `postgres: edb regression [local] EXPLAIN
> '.
> > Program terminated with signal 6, Aborted.
> > #0 0x00007f7d339ba277 in raise () from /lib64/libc.so.6
> > Missing separate debuginfos, use: debuginfo-install
> glibc-2.17-222.el7.x86_64 keyutils-libs-1.5.8-3.el7.x86_64
> krb5-libs-1.15.1-19.el7.x86_64 libcom_err-1.42.9-12.el7_5.x86_64
> libgcc-4.8.5-39.el7.x86_64 libselinux-2.5-12.el7.x86_64
> openssl-libs-1.0.2k-19.el7.x86_64 pcre-8.32-17.el7.x86_64
> zlib-1.2.7-17.el7.x86_64
> > (gdb) bt
> > #0 0x00007f7d339ba277 in raise () from /lib64/libc.so.6
> > #1 0x00007f7d339bb968 in abort () from /lib64/libc.so.6
> > #2 0x0000000000b0fbc3 in ExceptionalCondition (conditionName=0xcbda10
> "part_index >= 0", errorType=0xcbd1c3 "FailedAssertion", fileName=0xcbd2fe
> "partbounds.c", lineNumber=1957)
> > at assert.c:69
> > #3 0x0000000000892aa1 in is_dummy_partition (rel=0x19b37c0,
> part_index=-1) at partbounds.c:1957
> > #4 0x00000000008919bd in merge_list_bounds (partnatts=1,
> partsupfunc=0x1922798, partcollation=0x1922738, outer_rel=0x19b37c0,
> inner_rel=0x1922938, jointype=JOIN_INNER,
> > outer_parts=0x7fffd67751b0, inner_parts=0x7fffd67751a8) at
> partbounds.c:1529
> > #5 0x00000000008910de in partition_bounds_merge (partnatts=1,
> partsupfunc=0x1922798, partcollation=0x1922738, outer_rel=0x19b37c0,
> inner_rel=0x1922938, jointype=JOIN_INNER,
> > outer_parts=0x7fffd67751b0, inner_parts=0x7fffd67751a8) at
> partbounds.c:1223
> > #6 0x000000000082c41a in compute_partition_bounds (root=0x1a19ed0,
> rel1=0x19b37c0, rel2=0x1922938, joinrel=0x1ab7f30,
> parent_sjinfo=0x7fffd67752a0, parts1=0x7fffd67751b0,
> > parts2=0x7fffd67751a8) at joinrels.c:1644
> > #7 0x000000000082bc34 in try_partitionwise_join (root=0x1a19ed0,
> rel1=0x19b37c0, rel2=0x1922938, joinrel=0x1ab7f30,
> parent_sjinfo=0x7fffd67752a0, parent_restrictlist=0x1ab3318)
> > at joinrels.c:1402
> > #8 0x000000000082aea2 in populate_joinrel_with_paths (root=0x1a19ed0,
> rel1=0x19b37c0, rel2=0x1922938, joinrel=0x1ab7f30, sjinfo=0x7fffd67752a0,
> restrictlist=0x1ab3318)
> > at joinrels.c:926
> > #9 0x000000000082a8f5 in make_join_rel (root=0x1a19ed0, rel1=0x19b37c0,
> rel2=0x1922938) at joinrels.c:760
> > #10 0x0000000000829e03 in make_rels_by_clause_joins (root=0x1a19ed0,
> old_rel=0x19b37c0, other_rels_list=0x1ab2970, other_rels=0x1ab2990) at
> joinrels.c:312
> > #11 0x00000000008298d9 in join_search_one_level (root=0x1a19ed0,
> level=2) at joinrels.c:123
> > #12 0x000000000080c566 in standard_join_search (root=0x1a19ed0,
> levels_needed=2, initial_rels=0x1ab2970) at allpaths.c:3020
> > #13 0x000000000080c4df in make_rel_from_joinlist (root=0x1a19ed0,
> joinlist=0x199d538) at allpaths.c:2951
> > #14 0x000000000080816b in make_one_rel (root=0x1a19ed0,
> joinlist=0x199d538) at allpaths.c:228
> > #15 0x000000000084491d in query_planner (root=0x1a19ed0,
> qp_callback=0x84a538 <standard_qp_callback>, qp_extra=0x7fffd6775630) at
> planmain.c:276
> > #16 0x0000000000847040 in grouping_planner (root=0x1a19ed0,
> tuple_fraction=0) at planner.c:1447
> > #17 0x0000000000846709 in subquery_planner (glob=0x19b39d8,
> parse=0x1aaa290, parent_root=0x0, hasRecursion=false, tuple_fraction=0) at
> planner.c:1025
> > #18 0x0000000000844f3e in standard_planner (parse=0x1aaa290,
> > query_string=0x1830fa0 "EXPLAIN (COSTS OFF)\nSELECT t1.a, t1.c,
> t2.a, t2.c FROM plt1_adv t1 INNER JOIN plt2_adv t2 ON (t1.a = t2.a AND t1.c
> = t2.c) WHERE t1.b < 10 ORDER BY t1.a;", cursorOptions=2048,
> boundParams=0x0) at planner.c:406
> > #19 0x0000000000844ce9 in planner (parse=0x1aaa290,
> > query_string=0x1830fa0 "EXPLAIN (COSTS OFF)\nSELECT t1.a, t1.c,
> t2.a, t2.c FROM plt1_adv t1 INNER JOIN plt2_adv t2 ON (t1.a = t2.a AND t1.c
> = t2.c) WHERE t1.b < 10 ORDER BY t1.a;", cursorOptions=2048,
> boundParams=0x0) at planner.c:277
> > #20 0x0000000000978483 in pg_plan_query (querytree=0x1aaa290,
> > query_string=0x1830fa0 "EXPLAIN (COSTS OFF)\nSELECT t1.a, t1.c,
> t2.a, t2.c FROM plt1_adv t1 INNER JOIN plt2_adv t2 ON (t1.a = t2.a AND t1.c
> = t2.c) WHERE t1.b < 10 ORDER BY t1.a;", cursorOptions=2048,
> boundParams=0x0) at postgres.c:847
> > #21 0x00000000006937fc in ExplainOneQuery (query=0x1aaa290,
> cursorOptions=2048, into=0x0, es=0x19b36f0,
> > queryString=0x1830fa0 "EXPLAIN (COSTS OFF)\nSELECT t1.a, t1.c, t2.a,
> t2.c FROM plt1_adv t1 INNER JOIN plt2_adv t2 ON (t1.a = t2.a AND t1.c =
> t2.c) WHERE t1.b < 10 ORDER BY t1.a;",
> > params=0x0, queryEnv=0x0) at explain.c:397
> > #22 0x0000000000693351 in ExplainQuery (pstate=0x197c410,
> stmt=0x1aaa0b0, params=0x0, dest=0x197c378) at explain.c:281
> > #23 0x00000000009811fa in standard_ProcessUtility (pstmt=0x1a0bfc8,
> > queryString=0x1830fa0 "EXPLAIN (COSTS OFF)\nSELECT t1.a, t1.c, t2.a,
> t2.c FROM plt1_adv t1 INNER JOIN plt2_adv t2 ON (t1.a = t2.a AND t1.c =
> t2.c) WHERE t1.b < 10 ORDER BY t1.a;",
> > readOnlyTree=false, context=PROCESS_UTILITY_TOPLEVEL, params=0x0,
> queryEnv=0x0, dest=0x197c378, qc=0x7fffd6775f90) at utility.c:845
> > #24 0x00000000009809ec in ProcessUtility (pstmt=0x1a0bfc8,
> > queryString=0x1830fa0 "EXPLAIN (COSTS OFF)\nSELECT t1.a, t1.c, t2.a,
> t2.c FROM plt1_adv t1 INNER JOIN plt2_adv t2 ON (t1.a = t2.a AND t1.c =
> t2.c) WHERE t1.b < 10 ORDER BY t1.a;",
> > readOnlyTree=false, context=PROCESS_UTILITY_TOPLEVEL, params=0x0,
> queryEnv=0x0, dest=0x197c378, qc=0x7fffd6775f90) at utility.c:527
> > #25 0x000000000097f636 in PortalRunUtility (portal=0x1893b40,
> pstmt=0x1a0bfc8, isTopLevel=true, setHoldSnapshot=true, dest=0x197c378,
> qc=0x7fffd6775f90) at pquery.c:1147
> > #26 0x000000000097f3a5 in FillPortalStore (portal=0x1893b40,
> isTopLevel=true) at pquery.c:1026
> > #27 0x000000000097ed11 in PortalRun (portal=0x1893b40,
> count=9223372036854775807, isTopLevel=true, run_once=true, dest=0x1a0c0b8,
> altdest=0x1a0c0b8, qc=0x7fffd6776150) at pquery.c:758
> > #28 0x0000000000978aa5 in exec_simple_query (
> >
> > Thanks & Regards,
> > Rajkumar Raghuwanshi
> >
> >
> > On Fri, Sep 3, 2021 at 7:17 PM Amit Langote <amitlangote09(at)gmail(dot)com>
> wrote:
> >>
> >> On Wed, Sep 1, 2021 at 2:31 PM Amit Langote <amitlangote09(at)gmail(dot)com>
> wrote:
> >> > On Tue, Aug 31, 2021 at 8:02 PM Nitin Jadhav
> >> > <nitinjadhavpostgres(at)gmail(dot)com> wrote:
> >> > > The attached patch also fixes the above comments.
> >> >
> >> > I noticed that multi-column list partitions containing NULLs don't
> >> > work correctly with partition pruning yet.
> >> >
> >> > create table p0 (a int, b text, c bool) partition by list (a, b, c);
> >> > create table p01 partition of p0 for values in ((1, 1, true), (NULL,
> 1, false));
> >> > create table p02 partition of p0 for values in ((1, NULL, false));
> >> > explain select * from p0 where a is null;
> >> > QUERY PLAN
> >> > --------------------------------------------------------
> >> > Seq Scan on p01 p0 (cost=0.00..22.50 rows=6 width=37)
> >> > Filter: (a IS NULL)
> >> > (2 rows)
> >> >
> >> > I guess that may be due to the following newly added code being
> incomplete:
> >> >
> >> > +/*
> >> > + * get_partition_bound_null_index
> >> > + *
> >> > + * Returns the partition index of the partition bound which accepts
> NULL.
> >> > + */
> >> > +int
> >> > +get_partition_bound_null_index(PartitionBoundInfo boundinfo)
> >> > +{
> >> > + int i = 0;
> >> > + int j = 0;
> >> > +
> >> > + if (!boundinfo->isnulls)
> >> > + return -1;
> >> >
> >> > - if (!val->constisnull)
> >> > - count++;
> >> > + for (i = 0; i < boundinfo->ndatums; i++)
> >> > + {
> >> > + //TODO: Handle for multi-column cases
> >> > + for (j = 0; j < 1; j++)
> >> > + {
> >> > + if (boundinfo->isnulls[i][j])
> >> > + return boundinfo->indexes[i];
> >> > }
> >> > }
> >> >
> >> > + return -1;
> >> > +}
> >> >
> >> > Maybe this function needs to return a "bitmapset" of indexes, because
> >> > multiple partitions can now contain NULL values.
> >> >
> >> > Some other issues I noticed and suggestions for improvement:
> >> >
> >> > +/*
> >> > + * checkForDuplicates
> >> > + *
> >> > + * Returns TRUE if the list bound element is already present in the
> list of
> >> > + * list bounds, FALSE otherwise.
> >> > + */
> >> > +static bool
> >> > +checkForDuplicates(List *source, List *searchElem)
> >> >
> >> > This function name may be too generic. Given that it is specific to
> >> > implementing list bound de-duplication, maybe the following signature
> >> > is more appropriate:
> >> >
> >> > static bool
> >> > checkListBoundDuplicated(List *list_bounds, List *new_bound)
> >> >
> >> > Also, better if the function comment mentions those parameter names,
> like:
> >> >
> >> > "Returns TRUE if the list bound element 'new_bound' is already present
> >> > in the target list 'list_bounds', FALSE otherwise."
> >> >
> >> > +/*
> >> > + * transformPartitionListBounds
> >> > + *
> >> > + * Converts the expressions of list partition bounds from the raw
> grammar
> >> > + * representation.
> >> >
> >> > A sentence about the result format would be helpful, like:
> >> >
> >> > The result is a List of Lists of Const nodes to account for the
> >> > partition key possibly containing more than one column.
> >> >
> >> > + int i = 0;
> >> > + int j = 0;
> >> >
> >> > Better to initialize such loop counters closer to the loop.
> >> >
> >> > + colname[i] = (char *) palloc0(NAMEDATALEN * sizeof(char));
> >> > + colname[i] = get_attname(RelationGetRelid(parent),
> >> > + key->partattrs[i], false);
> >> >
> >> > The palloc in the 1st statement is wasteful, because the 2nd statement
> >> > overwrites its pointer by the pointer to the string palloc'd by
> >> > get_attname().
> >> >
> >> > + ListCell *cell2 = NULL;
> >> >
> >> > No need to explicitly initialize the loop variable.
> >> >
> >> > + RowExpr *rowexpr = NULL;
> >> > +
> >> > + if (!IsA(expr, RowExpr))
> >> > + ereport(ERROR,
> >> > + (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
> >> > + errmsg("Invalid list bound specification"),
> >> > + parser_errposition(pstate, exprLocation((Node
> >> > *) spec))));
> >> > +
> >> > + rowexpr = (RowExpr *) expr;
> >> >
> >> > It's okay to assign rowexpr at the top here instead of the dummy
> >> > NULL-initialization and write the condition as:
> >> >
> >> > if (!IsA(rowexpr, RowExpr))
> >> >
> >> > + if (isDuplicate)
> >> > + continue;
> >> > +
> >> > + result = lappend(result, values);
> >> >
> >> > I can see you copied this style from the existing code, but how about
> >> > writing this simply as:
> >> >
> >> > if (!isDuplicate)
> >> > result = lappend(result, values);
> >> >
> >> > -/* One value coming from some (index'th) list partition */
> >> > +/* One bound of a list partition */
> >> > typedef struct PartitionListValue
> >> > {
> >> > int index;
> >> > - Datum value;
> >> > + Datum *values;
> >> > + bool *isnulls;
> >> > } PartitionListValue;
> >> >
> >> > Given that this is a locally-defined struct, I wonder if it makes
> >> > sense to rename the struct while we're at it. Call it, say,
> >> > PartitionListBound?
> >> >
> >> > Also, please keep part of the existing comment that says that the
> >> > bound belongs to index'th partition.
> >> >
> >> > Will send more comments in a bit...
> >>
> >> + * partition_bound_accepts_nulls
> >> + *
> >> + * Returns TRUE if partition bound has NULL value, FALSE otherwise.
> >> */
> >>
> >> I suggest slight rewording, as follows:
> >>
> >> "Returns TRUE if any of the partition bounds contains a NULL value,
> >> FALSE otherwise."
> >>
> >> - PartitionListValue *all_values;
> >> + PartitionListValue **all_values;
> >> ...
> >> - all_values = (PartitionListValue *)
> >> - palloc(ndatums * sizeof(PartitionListValue));
> >> + ndatums = get_list_datum_count(boundspecs, nparts);
> >> + all_values = (PartitionListValue **)
> >> + palloc(ndatums * sizeof(PartitionListValue *));
> >>
> >> I don't see the need to redefine all_values's pointer type. No need
> >> to palloc PartitionListValue repeatedly for every datum as done
> >> further down as follows:
> >>
> >> + all_values[j] = (PartitionListValue *)
> >> palloc(sizeof(PartitionListValue));
> >>
> >> You do need the following two though:
> >>
> >> + all_values[j]->values = (Datum *) palloc0(key->partnatts *
> >> sizeof(Datum));
> >> + all_values[j]->isnulls = (bool *) palloc0(key->partnatts *
> >> sizeof(bool));
> >>
> >> If you change the above the way I suggest, you'd also need to revert
> >> the following change:
> >>
> >> - qsort_arg(all_values, ndatums, sizeof(PartitionListValue),
> >> + qsort_arg(all_values, ndatums, sizeof(PartitionListValue *),
> >> qsort_partition_list_value_cmp, (void *) key);
> >>
> >> + int orig_index = all_values[i]->index;
> >> + boundinfo->datums[i] = (Datum *) palloc(key->partnatts *
> sizeof(Datum));
> >>
> >> Missing a newline between these two statements.
> >>
> >> BTW, I noticed that the boundDatums variable is no longer used in
> >> create_list_bounds. I traced back its origin and found that a recent
> >> commit 53d86957e98 introduced it to implement an idea to reduce the
> >> finer-grained pallocs that were being done in create_list_bounds(). I
> >> don't think that this patch needs to throw away that work. You can
> >> make it work as the attached delta patch that applies on top of v3.
> >> Please check.
> >>
> >> @@ -915,7 +949,7 @@ partition_bounds_equal(int partnatts, int16
> >> *parttyplen, bool *parttypbyval,
> >> if (b1->nindexes != b2->nindexes)
> >> return false;
> >>
> >> - if (b1->null_index != b2->null_index)
> >> + if (get_partition_bound_null_index(b1) !=
> >> get_partition_bound_null_index(b2))
> >>
> >> As mentioned in the last message, this bit in partition_bounds_equal()
> >> needs to be comparing "bitmapsets" of null bound indexes, that is
> >> after fixing get_partition_bound_null_index() as previously mentioned.
> >>
> >> But...
> >>
> >> @@ -988,7 +1022,22 @@ partition_bounds_equal(int partnatts, int16
> >> *parttyplen, bool *parttypbyval,
> >> * context. datumIsEqual() should be simple enough to
> be
> >> * safe.
> >> */
> >> - if (!datumIsEqual(b1->datums[i][j], b2->datums[i][j],
> >> + if (b1->isnulls)
> >> + b1_isnull = b1->isnulls[i][j];
> >> + if (b2->isnulls)
> >> + b2_isnull = b2->isnulls[i][j];
> >> +
> >> + /*
> >> + * If any of the partition bound has NULL value, then
> check
> >> + * equality for the NULL value instead of comparing the
> datums
> >> + * as it does not contain valid value in case of NULL.
> >> + */
> >> + if (b1_isnull || b2_isnull)
> >> + {
> >> + if (b1_isnull != b2_isnull)
> >> + return false;
> >> + }
> >>
> >> ...if you have this in the main loop, I don't think we need the above
> >> code stanza which appears to implement a short-cut for this long-form
> >> logic.
> >>
> >> + (key->strategy != PARTITION_STRATEGY_LIST ||
> >> + !src->isnulls[i][j]))
> >>
> >> I think it's better to write this condition as follows just like the
> >> accompanying condition involving src->kind:
> >>
> >> (src->nulls == NULL || !src->isnulls[i][j])
> >>
> >> (Skipped looking at merge_list_bounds() and related changes for now as
> >> I see a lot of TODOs remain to be done.)
> >>
> >> In check_new_partition_bound():
> >>
> >> + Datum *values = (Datum *)
> >> palloc0(key->partnatts * sizeof(Datum));
> >> + bool *isnulls = (bool *)
> >> palloc0(key->partnatts * sizeof(bool));
> >>
> >> Doesn't seem like a bad idea to declare these as:
> >>
> >> Datum values[PARTITION_MAX_KEYS];
> >> bool isnulls[PARTITION_MAX_KEYS];
> >>
> >>
> >> I looked at get_qual_for_list_multi_column() and immediately thought
> >> that it may be a bad idea. I think it's better to integrate the logic
> >> for multi-column case into the existing function even if that makes
> >> the function appear more complex. Having two functions with the same
> >> goal and mostly the same code is not a good idea mainly because it
> >> becomes a maintenance burden.
> >>
> >> I have attempted a rewrite such that get_qual_for_list() now handles
> >> both the single-column and multi-column cases. Changes included in
> >> the delta patch. The patch updates some outputs of the newly added
> >> tests for multi-column list partitions, because the new code emits the
> >> IS NOT NULL tests a bit differently than
> >> get_qual_for_list_mutli_column() would. Notably, the old approach
> >> would emit IS NOT NULL for every non-NULL datum matched to a given
> >> column, not just once for the column. However, the patch makes a few
> >> other tests fail, mainly because I had to fix
> >> partition_bound_accepts_nulls() to handle the multi-column case,
> >> though didn't bother to update all callers of it to also handle the
> >> multi-column case correctly. I guess that's a TODO you're going to
> >> deal with at some point anyway. :)
> >>
> >> I still have more than half of v3 left to look at, so will continue
> >> looking. In the meantime, please check the changes I suggested,
> >> including the delta patch, and let me know your thoughts.
> >>
> >> --
> >> Amit Langote
> >> EDB: http://www.enterprisedb.com
>