Mark Lewis wrote:
PG could scan the index looking for matches first and only load the
actual rows if it found a match, but that could only be a possible win
if there were very few matches, because the difference in cost between a
full index scan and a sequential scan would need to be greater than the
cost of randomly fetching all of the matching data rows from the table
to look up the visibility information.
Just out of curiosity: Does Postgress store a duplicate of the data in the index, even for long strings? I thought indexes only had to
store the string up to the point where there was no ambiguity, for example, if I have "missing", "mississippi" and
"misty", the index only needs "missin", "missis" and "mist" in the actual index. This would make
it impossible to use a full index scan for a LIKE query.
Craig
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