Cherry pick #116371 to 26.7: Fix a _table/_database filter over a Merge table returning no rows for children that read from other tables - #117025
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… that read from other tables The values of the `_table`/`_database` virtual columns are stamped by the table that actually produces the rows: the remote table for `Distributed`, the destination for `Buffer`, the target for `Alias`, the children for a nested `Merge`. But `ReadFromMerge::getSelectedTables` pruned children by their own names, so whenever a child reads its data from other tables, the two disagree and the query silently returned no rows. Prune only the children that do not read from other tables; the rest are always read, and the predicate filters their rows. A rework of #113735. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
In a database with the lazy_load_tables setting, an unloaded table is a StorageTableProxy, and StorageProxy did not forward the new readsFromOtherTables flag to the nested storage. A lazily loaded Distributed, Merge, Buffer, or Alias child of a Merge table would therefore still be pruned by a `_table`/`_database` filter by the proxy's own name, silently returning no rows after a restart or `ATTACH DATABASE`. Forward the flag like the other capability bits and add a `lazy_load_tables = 1` regression test. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The `various` style check (`ci/jobs/scripts/check_style/various_checks.sh`) requires every test querying `system.tables` to scope it to a single database, and recognizes only three spellings: `database ... currentDatabase`, `database ... $CLICKHOUSE_DATABASE`, and a quoted literal. The SQL query-parameter form `database = {CLICKHOUSE_DATABASE_1:String}` is equally scoped but matches none of them, so the check failed:
Queries to system.tables ... does not have database = currentDatabase()/$CLICKHOUSE_DATABASE condition in ./tests/queries/0_stateless/05045_merge_prefilter_lazy_load_tables.sql
Since the style check is a `run_after` dependency of the whole workflow, this dropped 151 jobs, including both `Bugfix validation (functional tests, *)` jobs, which in turn failed the `new_tests_check.py` post-hook in `Finish Workflow`, and the same failure blocked the `CH Inc sync` workflow.
Spell the probe with `currentDatabase()` under a `USE`, as `04870_column_declaration_statistics_lazy_load` already does for the same situation. `USE` does not load the lazily loaded tables, so the reported engine is still `TableProxy` and the reference file is unchanged.
CI report: https://s3.amazonaws.com/clickhouse-test-reports/json.html?PR=116371&sha=1193fcaafc2d139446ca246788530956cd79b7d8&name_0=PR
Related: #116371
…-children Fix a `_table`/`_database` filter over a `Merge` table returning no rows for children that read from other tables
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Original pull-request #116371
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