In #3901 the "Data received from worker(s)" sections were added to EXPLAIN
ANALYZE. After merging @pykello posted some review comments. This addresses
those comments as well as fixing a other issues that I found while addressing
them. The things this does:
1. Fix `EXPLAIN ANALYZE EXECUTE p1` to not increase received data on every
execution
2. Fix `EXPLAIN ANALYZE EXECUTE p1(1)` to not return 0 bytes as received data
allways.
3. Move `EXPLAIN ANALYZE` specific logic to `multi_explain.c` from
`adaptive_executor.c`
4. Change naming of new explain sections to `Tuple data received from node(s)`.
Firstly because a task can reference the coordinator too, so "worker(s)" was
incorrect. Secondly to indicate that this is tuple data and not all network
traffic that was performed.
5. Rename `totalReceivedData` in our codebase to `totalReceivedTupleData` to
make it clearer that it's a tuple data counter, not all network traffic.
6. Actually add `binary_protocol` test to `multi_schedule` (woops)
7. Fix a randomly failing test in `local_shard_execution.sql`.
Sometimes isolation tests get stuck in CI and we cannot see why, because
the job is killed by the CI runner. This will instead fail inside make
the testsuite continue, but mark it as a failure like this in the diff
output:
```diff
+isolationtester: canceling step s2-ddl-create-index-concurrently after 5 seconds
step s2-ddl-create-index-concurrently: CREATE INDEX CONCURRENTLY select_append_index ON select_append(id);
+ERROR: CONCURRENTLY-enabled index command failed
```
We should detect blockages very quickly and the queries we run are also
very fast, so 5 seconds should be more than enough to catch any random
slowness. The default from Postgres is 5 minutes, which is waaay to much
for us.
Shard id to index mapping stored in cache entry as there may now be multiple entries alive for a given relation
insert_select_executor: revert copying cache entry, which was a hack added to avoid memory safety issues
Sadly this does not actually work yet for binary protocol data, because
when doing EXPLAIN ANALYZE we send two commands at the same time. This
means we cannot use `SendRemoteCommandParams`, and thus cannot use the
binary protocol. This can still be useful though when using the text
protocol, to find out that a lot of data is being sent.
Due to the problem described in #3908 we don't cover the tdigest integration (and other extensions) on CI.
Due to this a bug got in the patch due to a change in `EXPLAIN VERBOSE` being merged concurrently with the tdigest integration. This PR fixes the test output that missed the newly added information.
* Insert select with master query
* Use relid to set custom_scan_tlist varno
* Reviews
* Fixes null check
Co-authored-by: Marco Slot <marco.slot@gmail.com>
This can save a lot of data to be sent in some cases, thus improving
performance for which inter query bandwidth is the bottleneck.
There's some issues with enabling this as default, so that's currently not done.
DESCRIPTION: Adds support to partially push down tdigest aggregates
tdigest extensions: https://github.com/tvondra/tdigest
This PR implements the partial pushdown of tdigest calculations when possible. The extension adds a tdigest type which can be combined into the same structure. There are several aggregate functions that can be used to get;
- a quantile
- a list of quantiles
- the quantile of a hypothetical value
- a list of quantiles for a list of hypothetical values
These function can work both on values or tdigest types.
Since we can create tdigest values either by combining them, or based on a group of values we can rewrite the aggregates in such a way that most of the computation gets delegated to the compute on the shards. This both speeds up the percentile calculations because the values don't have to be sorted while at the same time making the transfer size from the shards to the coordinator significantly less.
We still recursively plan some cases, eg:
- INSERTs
- SELECT FOR UPDATE when reference tables in query
- Everything must be same single shard & replication model
We wrap worker tasks in worker_save_query_explain_analyze() so we can fetch
their explain output later by a call worker_last_saved_explain_analyze().
Fixes#3519Fixes#2347Fixes#2613Fixes#621
This code is not needed anymore since #3668 was merged.
It's actually causing some issues when using the binary Postgres
protocol, because postgres thinks it gets a `bigint` from
the worker, but actually gets an normal `int`.
The query in question that fails is this:
```sql
CREATE TABLE test_table_1(id int, val1 int);
CREATE TABLE test_table_2(id int, val1 bigint);
SELECT create_distributed_table('test_table_1', 'id');
SELECT create_distributed_table('test_table_2', 'id');
INSERT INTO test_table_1 VALUES(1,1),(2,2),(3,3);
INSERT INTO test_table_2 VALUES(1,1),(3,3),(4,5);
SELECT val1
FROM test_table_1 LEFT JOIN test_table_2 USING(id, val1)
ORDER BY 1;
```
The difference in queries that is sent to the workers after this change is this, for this query:
```diff
--- query_old.sql 2020-06-09 09:51:21.460000000 +0200
+++ query_new.sql 2020-06-09 09:51:39.500000000 +0200
@@ -1 +1 @@
-SELECT worker_column_1 AS val1 FROM (SELECT test_table_1.val1 AS worker_column_1 FROM (public.test_table_1_102015 test_table_1(id, val1) LEFT JOIN public.test_table_2_102019 test_table_2(id, val1) USING (id, val1))) worker_subquery
+SELECT worker_column_1 AS val1 FROM (SELECT val1 AS worker_column_1 FROM (public.test_table_1_102015 test_table_1(id, val1) LEFT JOIN public.test_table_2_102019 test_table_2(id, val1) USING (id, val1))) worker_subquery
```
This is a different version of #3634. It also removes SwallowErrors, but
instead of modifying our own functions to not throw errors, it uses the
postgres built in `PathNameDeleteTemporaryDir` function. This function
does not throw errors.
Since this change is for a bugfix, I tried to minimize the changes.
PRs with the following changes would be good to do separately from this
PR:
1. Use PathName(Create|Open|Delete)Temporary(File|Dir) to open and
remove all files/dirs instead of our own custom file functions.
2. Prefix our outmost files/directories with `PG_TEMP_FILE_PREFIX` so
that they are identified by Postgres as temporary files, which will be
removed at postmaster start. This way we do not have to do this cleanup
ourselves.
3. Store the files in the temporary table space if it exists.
Fixes#3634Fixes#3618
Implements worker_save_query_explain_analyze and worker_last_saved_explain_analyze.
worker_save_query_explain_analyze executes and returns results of query while
saving its EXPLAIN ANALYZE to be fetched later.
worker_last_saved_explain_analyze returns the saved EXPLAIN ANALYZE result.
If we want to get necessary lockmode for a relation RangeVar within
a query, we can get the lockmode easily from the RangeVar itself (if
pg version >= 12).
However, if we want to decide the lockmode appropriate for the
"query", we can derive this information by using GetQueryLockMode
according to the code comment from RangeTblEntry->rellockmode.
Implements a new `TupleDestination` interface to allow custom tuple processing per task.
This can be specially useful if a task contains multiple queries. An example of this EXPLAIN
ANALYZE, where it needs to add some UDF calls to the query to fetch the explain output
from worker after fetching the actual query results.
We should check the remove type in IsDropCitusStmt because if the remove
type is not OBJECT_EXTENSION then the stored objects in
dropStmt->objects may not be of type Value. This was crashing PG-13.
Also rename the method as IsDropCitusExtensionStmt.
To reduce code duplication, implement function that pushes search_path
to be NIL and sets addCatalog to true so that all objects outside of
pg_catalog will be schema-prefixed.
Append IF NOT EXISTS to CREATE SERVER commands generated by
pg_get_serverdef_string function when deparsing an existing server
object that a foreign table depends.
SELECT_TASK is renamed to READ_TASK as a SELECT with modifying CTEs will be a MODIFYING_TASK
RouterInsertJob: Assert originalQuery->commandType == CMD_INSERT
CreateModifyPlan: Assert originalQuery->commandType != CMD_SELECT
Remove unused function IsModifyDistributedPlan
DistributedExecution, ExecutionParams, DistributedPlan: Rename hasReturning to expectResults
SELECTs set expectResults to true
Rename CreateSingleTaskRouterPlan to CreateSingleTaskRouterSelectPlan
Do not release AccessShareLock when closing pg_constraint to prevent
modifications to be done on pg_constraint to make sure that caller
will process valid foreign key constraints through the transaction.
Marco Slot
Jelte Fennema
Philip Dubé
SaitTalhaNisanci
Hadi Moshayedi
Nils Dijk
Halil Ozan Akgül
Onder Kalaci
Onur Tirtir