Revision 3097
Added by Aaron Marcuse-Kubitza about 12 years ago
| lib/sql.py | ||
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| 1228 | 1228 |
'''Creates a copy of a temp table which is distinct on the given columns. |
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The table will get an index on these columns, facilitating merge joins. |
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@param table Will be renamed to the distinct on table. |
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@param distinct_on If empty, creates a table with one row. This is useful if |
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your distinct_on columns are all literal values. |
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@return The old table. |
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''' |
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if distinct_on == []: return table # already distinct |
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|
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old_table = copy.copy(table) |
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table.name = sql_gen.concat(table.name, '_distinct') |
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|
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copy_table_struct(db, old_table, table) |
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add_index(db, distinct_on, table, unique=True) |
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insert_select(db, table, None, mk_select(db, old_table, start=0), |
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ignore=True) |
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|
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limit = None |
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if distinct_on == []: limit = 1 # one sample row |
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else: add_index(db, distinct_on, table, unique=True) |
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|
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insert_select(db, table, None, mk_select(db, old_table, start=0, |
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limit=limit), ignore=True) |
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analyze(db, table) |
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return old_table |
Also available in: Unified diff
sql.py: distinct_table(): Fixed bug where empty distinct_on cols needed to create a table with one sample row, instead of returning the original table, because this indicates that the full set of distinct_on columns are all literal values and should only occur once