exploit iceberg row-count metadata #74
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added 2 commits
October 9, 2024 14:09
Examine the row-counts in the manifest and count how many rows are in the (existing or added) data an deletion files. Use these two counts to pass the new named_parameter "explicit_cardinality" into the generated parquet_scans. Note that because iceberg is passing in an explicit schema into the parquet_scan, it does not open any file during bind. That means the parquet_scans it generates did not have any cardinality information during query optimization. That can cause rather bad query plans. This PR (pb/explicit-iceberg-cardinality) fixes that. Note that this PR needs the DuckDB PR pb/exicit-parquet-cardinality that adds the "explicit_cardinality" named_parameter to parquet_scan.
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This CI is expected to fail (unknown named_parameter 'explicit_cardinality') until duckdb/duckdb#14292 would have been merged |
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Examine the row-counts in the manifest and count how many rows are in the (existing or added) data resp. deletion files.
Use these two counts to pass the new named_parameter "explicit_cardinality" into the generated parquet_scans.
Note that because iceberg is passing in an explicit schema into the parquet_scan, it does not open any file during bind. That means the parquet_scans it generates did not have any cardinality information during query optimization.
That can cause rather bad query plans. This PR (pb/explicit-iceberg-cardinality) fixes that. Note that this PR needs the DuckDB PR pb/explicit-parquet-cardinality that adds the "explicit_cardinality" named_parameter to parquet_scan.