Minor: Document parquet_metadata function
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alamb
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Jan 13, 2024
| @@ -191,7 +191,7 @@ DataFusion CLI v16.0.0 | |||
| 2 rows in set. Query took 0.007 seconds. | |||
| ``` | |||
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| ## Creating external tables | |||
| ## Creating External Tables | |||
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drive by cleanup -- the other headings are capitalized so it seemed strange that this one was not
| @@ -467,6 +474,66 @@ Available commands inside DataFusion CLI are: | |||
| > SET datafusion.execution.batch_size to 1024; | |||
| ``` | |||
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| - `parquet_metadata` table function | |||
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comphead
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Jan 13, 2024
comphead
reviewed
Jan 13, 2024
comphead
reviewed
Jan 13, 2024
| | stats_max | Utf8 | The minimum value for this column chunk, if stored in the statistics, cast to a string | | ||
| | stats_null_count | Int64 | Number of null values in this column chunk, if stored in the statistics | | ||
| | stats_distinct_count | Int64 | Number of distinct values in this column chunk, if stored in the statistics | | ||
| | stats_min_value | Utf8 | Same as `stats_min` | |
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wondering if this duplicated fields needed?
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I don't honestly know why the seemingly duplicated columns are present. It was done initially to mirror duckdb which has them. Maybe we should investigate the reason why 🤔
D create table foo as select * from parquet_metadata('./benchmarks/data/hits.parquet');
D describe table foo;
┌─────────────────────────┬─────────────┬─────────┬─────────┬─────────┬─────────┐
│ column_name │ column_type │ null │ key │ default │ extra │
│ varchar │ varchar │ varchar │ varchar │ varchar │ varchar │
├─────────────────────────┼─────────────┼─────────┼─────────┼─────────┼─────────┤
│ file_name │ VARCHAR │ YES │ │ │ │
│ row_group_id │ BIGINT │ YES │ │ │ │
│ row_group_num_rows │ BIGINT │ YES │ │ │ │
│ row_group_num_columns │ BIGINT │ YES │ │ │ │
│ row_group_bytes │ BIGINT │ YES │ │ │ │
│ column_id │ BIGINT │ YES │ │ │ │
│ file_offset │ BIGINT │ YES │ │ │ │
│ num_values │ BIGINT │ YES │ │ │ │
│ path_in_schema │ VARCHAR │ YES │ │ │ │
│ type │ VARCHAR │ YES │ │ │ │
│ stats_min │ VARCHAR │ YES │ │ │ │
│ stats_max │ VARCHAR │ YES │ │ │ │
│ stats_null_count │ BIGINT │ YES │ │ │ │
│ stats_distinct_count │ BIGINT │ YES │ │ │ │
│ stats_min_value │ VARCHAR │ YES │ │ │ │
│ stats_max_value │ VARCHAR │ YES │ │ │ │
│ compression │ VARCHAR │ YES │ │ │ │
│ encodings │ VARCHAR │ YES │ │ │ │
│ index_page_offset │ BIGINT │ YES │ │ │ │
│ dictionary_page_offset │ BIGINT │ YES │ │ │ │
│ data_page_offset │ BIGINT │ YES │ │ │ │
│ total_compressed_size │ BIGINT │ YES │ │ │ │
│ total_uncompressed_size │ BIGINT │ YES │ │ │ │
├─────────────────────────┴─────────────┴─────────┴─────────┴─────────┴─────────┤
│ 23 rows 6 columns │
└───────────────────────────────────────────────────────────────────────────────┘
Co-authored-by: comphead <comphead@users.noreply.github.com>
alamb
changed the title
parquet_metadata function
comphead
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Jan 14, 2024
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Which issue does this PR close?
Part of #7013
Rationale for this change
I was writing a blog post about DataFusion apache/arrow-site#457 and I wanted to highlight this feature that @Veeupup added in #8367 but it wasn't documented
What changes are included in this PR?
Document the function
Are these changes tested?
N/A
Are there any user-facing changes?
More docs