ARROW-12108: [Rust] [DataFusion] Implement SHOW TABLES #9847
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nevi-me
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FYI @Dandandan @returnString @andygrove -- what do you think about adding support for |
jorgecarleitao
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! Nice and sweet. Also, great coverage 👍
returnString
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Great stuff - I think it's super useful as an accessible way to view the catalog structure outside of GUI tooling :) |
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Thanks all! |
alamb
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# Rationale Accessing the list of columns via `select * from information_schema.columns` (introduced in #9840) is a lot to type See the doc for background: https://docs.google.com/document/d/12cpZUSNPqVH9Z0BBx6O8REu7TFqL-NPPAYCUPpDls1k/edit# This is a sister PR to `SHOW TABLES` here: #9847 # Proposal Add support for `SHOW COLUMNS FROM <table>` command. Following the MySQL syntax supported by sqlparser: https://dev.mysql.com/doc/refman/8.0/en/show-columns.html # Example Use Setup: ``` echo "1,Foo,44.9" > /tmp/table.csv echo "2,Bar,22.1" >> /tmp/table.csv cargo run --bin datafusion-cli ``` Then run : ``` > CREATE EXTERNAL TABLE t(a int, b varchar, c float) STORED AS CSV LOCATION '/tmp/table.csv'; 0 rows in set. Query took 0 seconds. > show columns from t; +---------------+--------------+------------+-------------+-----------+-------------+ | table_catalog | table_schema | table_name | column_name | data_type | is_nullable | +---------------+--------------+------------+-------------+-----------+-------------+ | datafusion | public | t | a | Int32 | NO | | datafusion | public | t | b | Utf8 | NO | | datafusion | public | t | c | Float32 | NO | +---------------+--------------+------------+-------------+-----------+-------------+ 3 row in set. Query took 0 seconds. ``` # Commentary Note that the identifiers are case sensitive (which is a more general problem that affects all name resolution, not just `SHOW COLUMNS`). Ideally this should also work: ``` > show columns from T; Plan("Unknown relation for SHOW COLUMNS: T") > select * from T; Plan("Table or CTE with name \'T\' not found") ``` Closes #9866 from alamb/alamb/show_columns Authored-by: Andrew Lamb <[email protected]> Signed-off-by: Andrew Lamb <[email protected]>
pachadotdev
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# Rationale Accessing the list of columns via `select * from information_schema.columns` (introduced in apache#9840) is a lot to type See the doc for background: https://docs.google.com/document/d/12cpZUSNPqVH9Z0BBx6O8REu7TFqL-NPPAYCUPpDls1k/edit# This is a sister PR to `SHOW TABLES` here: apache#9847 # Proposal Add support for `SHOW COLUMNS FROM <table>` command. Following the MySQL syntax supported by sqlparser: https://dev.mysql.com/doc/refman/8.0/en/show-columns.html # Example Use Setup: ``` echo "1,Foo,44.9" > /tmp/table.csv echo "2,Bar,22.1" >> /tmp/table.csv cargo run --bin datafusion-cli ``` Then run : ``` > CREATE EXTERNAL TABLE t(a int, b varchar, c float) STORED AS CSV LOCATION '/tmp/table.csv'; 0 rows in set. Query took 0 seconds. > show columns from t; +---------------+--------------+------------+-------------+-----------+-------------+ | table_catalog | table_schema | table_name | column_name | data_type | is_nullable | +---------------+--------------+------------+-------------+-----------+-------------+ | datafusion | public | t | a | Int32 | NO | | datafusion | public | t | b | Utf8 | NO | | datafusion | public | t | c | Float32 | NO | +---------------+--------------+------------+-------------+-----------+-------------+ 3 row in set. Query took 0 seconds. ``` # Commentary Note that the identifiers are case sensitive (which is a more general problem that affects all name resolution, not just `SHOW COLUMNS`). Ideally this should also work: ``` > show columns from T; Plan("Unknown relation for SHOW COLUMNS: T") > select * from T; Plan("Table or CTE with name \'T\' not found") ``` Closes apache#9866 from alamb/alamb/show_columns Authored-by: Andrew Lamb <[email protected]> Signed-off-by: Andrew Lamb <[email protected]>
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Rationale
Accessing the list of tables via
select * from information_schema.tables(introduced in #9818) is a lot to typeSee the doc for background: https://docs.google.com/document/d/12cpZUSNPqVH9Z0BBx6O8REu7TFqL-NPPAYCUPpDls1k/edit#
Proposal
Add support for
SHOW TABLEScommand.Commentary
This is different than both postgres (which uses
\dinpsqlfor this purpose), and MySQL (which usesDESCRIBE).I could be convinced that we should not add
SHOW TABLESat all (and just stay withselect * from information_schema.tablesbut I wanted to add the proposal)Example Use
Setup:
Then run :