voodoo index usage ;)

perhaps the db gawds can explain this....

# \d radusage
Table "radusage"
Attribute | Type | Modifier
-----------+-------------+----------
datetime | timestamp | not null
account | varchar(64) |
usage | integer |
sent | integer |
recv | integer |
ip | bigint |
host | bigint |
port | smallint |
Indices: idxradaccount,
idxraddate,
idxradoid

# \d idxradaccount
Index "idxradaccount"
Attribute | Type
-----------+-------------
account | varchar(64)
btree

# \d idxraddate
Index "idxraddate"
Attribute | Type
-----------+-----------
datetime | timestamp
btree

# explain select * from radusage where account = 'someuser';
NOTICE: QUERY PLAN:

Seq Scan on radusage (cost=0.00..13870.80 rows=5674 width=50)

and if i add in datetime (without effectively changing the semantic
meaning of the search)

# explain select * from radusage where account = 'someuser' and datetime >
'1900-01-01';
NOTICE: QUERY PLAN:

Index Scan using idxradaccount on radusage (cost=0.00..15295.37 rows=5668
width=50)

first case doesn't use the index, the second does use what would seem to
be the correct index

isn't that wacky????

-duck

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