9e225ab447
Overview
Fixes #7355.
Before this changes, there were a few invalid results of aggregates/GROUP BY on tables with secondary indexes (see below).
Unfortunately, it still does NOT fix the problem in issue #7043. Although this PR moves forward fixing of that issue, there is still a bug with `TOKEN(...)` in `WHERE` clauses of indexed selects that is not addressed in this PR. It will be fixed in my next PR.
It does NOT fix the problems in issues #7432, #7431 as those are out-of-scope of this PR and do not affect the correctness of results (only return a too large page).
GROUP BY (first commit)
Before the change, `GROUP BY` `SELECT`s with some `WHERE` restrictions on an indexed column would return invalid results (same grouped column values appearing multiple times):
```
CREATE TABLE ks.t(pk int, ck int, v int, PRIMARY KEY(pk, ck));
CREATE INDEX ks_t on ks.t(v);
INSERT INTO ks.t(pk, ck, v) VALUES (1, 2, 3);
INSERT INTO ks.t(pk, ck, v) VALUES (1, 4, 3);
SELECT pk FROM ks.t WHERE v=3 GROUP BY pk;
pk
----
1
1
```
This is fixed by correctly passing `_group_by_cell_indices` to `result_set_builder`. Fixes the third failing example from issue #7355.
Paging (second commit)
Fixes two issues related to improper paging on indexed `SELECT`s. As those two issues are closely related (fixing one without fixing the other causes invalid results of queries), they are in a single commit (second commit).
The first issue is that when using `slice.set_range`, the existing `_row_ranges` (which specify clustering key prefixes) are not taken into account. This caused the wrong rows to be included in the result, as the clustering key bound was set to a half-open range:
```
CREATE TABLE ks.t(a int, b int, c int, PRIMARY KEY ((a, b), c));
CREATE INDEX kst_index ON ks.t(c);
INSERT INTO ks.t(a, b, c) VALUES (1, 2, 3);
INSERT INTO ks.t(a, b, c) VALUES (1, 2, 4);
INSERT INTO ks.t(a, b, c) VALUES (1, 2, 5);
SELECT COUNT(*) FROM ks.t WHERE c = 3;
count
-------
2
```
The second commit fixes this issue by properly trimming `row_ranges`.
The second fixed problem is related to setting the `paging_state` to `internal_options`. It was improperly set to the value just after reading from index, making the base query start from invalid `paging_state`.
The second commit fixes this issue by setting the `paging_state` after both index and base table queries are done. Moreover, the `paging_state` is now set based on `paging_state` of index query and the results of base table query (as base query can return more rows than index query).
The second commit fixes the first two failing examples from issue #7355.
Tests (fourth commit)
Extensively tests queries on tables with secondary indices with aggregates and `GROUP BY`s.
Tests three cases that are implemented in `indexed_table_select_statement::do_execute` - `partition_slices`,
`whole_partitions` and (non-`partition_slices` and non-`whole_partitions`). As some of the issues found were related to paging, the tests check scenarios where the inserted data is smaller than a page, larger than a page and larger than two pages (and some in-between page boundaries scenarios).
I found all those parameters (case of `do_execute`, number of inserted rows) to have an impact of those fixed bugs, therefore the tests validate a large number of those scenarios.
Configurable internal_paging_size (third commit)
Before this change, internal `page_size` when doing aggregate, `GROUP BY` or nonpaged filtering queries was hard-coded to `DEFAULT_COUNT_PAGE_SIZE` (10,000). This change adds new internal_paging_size variable, which is configurable by `set_internal_paging_size` and `reset_internal_paging_size` free functions. This functionality is only meant for testing purposes.
Closes #7497
* github.com:scylladb/scylla:
tests: Add secondary index aggregates tests
select_statement: Introduce internal_paging_size
select_statement: Fix paging on indexed selects
select_statement: Fix GROUP BY on indexed select
(cherry picked from commit 8c645f74ce)
34 lines
902 B
C++
34 lines
902 B
C++
/*
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* Copyright (C) 2020 ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <seastar/core/future.hh>
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namespace cql3 {
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namespace statements {
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future<> set_internal_paging_size(int internal_paging_size);
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future<> reset_internal_paging_size();
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}
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}
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