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DROP TABLE IF EXISTS t1;
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CREATE TABLE t1 (g GEOMETRY REF_SYSTEM_ID=101);
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DROP TABLE IF EXISTS t2;
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CREATE TABLE t2 AS SELECT g AS g_column, COALESCE(g) AS g_coalesce FROM t1;
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DROP TABLE IF EXISTS t3;
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CREATE TABLE t3 AS SELECT g AS g_union FROM t1 UNION SELECT g FROM t1;
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SELECT G_TABLE_NAME, G_GEOMETRY_COLUMN, SRID FROM INFORMATION_SCHEMA.GEOMETRY_COLUMNS;
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returns
+--------------+-------------------+------+
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| G_TABLE_NAME | G_GEOMETRY_COLUMN | SRID |
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+--------------+-------------------+------+
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| t1 | g | 101 |
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| t2 | g_column | 101 |
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| t2 | g_coalesce | 0 |
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| t3 | g_union | 0 |
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+--------------+-------------------+------+
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Notice, g_column preserved the original REF_SYSTEM_ID, which is correct.
More complex cases (e.g. g_coalesce and g_union) did not, as they should.
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