> and I can see whether a sequential scan or an index scan is
> performed, but parsing the output of EXPLAIN programmatically
> is nearly impossible. Anyway the words 'Index Scan' and 'Seq
> Scan' can change without notice, maybe even from one locale to
> another.
I think you are operating under the faulty assumption that
'Index Scan' in EXPLAIN output signifies that a column is
*indexed*. What it really tells you is whether an index is
actually *used* when getting data from a column. That of
course requires an index to be there. However, an index being
there doesn't guarantee it being used.
Karsten
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TIP 9: the planner will ignore your desire to choose an index scan if your
joining column's datatypes do not match
