Why is a trigger faster than doing a ALTER after table is created? I
thought a trigger would be slower because it would be invoked every
iteration (a new row is inserted) during the COPY process.
Benjamin
On Aug 26, 2007, at 8:43 PM, Tom Lane wrote:
Gregory Stark <stark@xxxxxxxxxxxxxxxx> writes:
On Sun, 26 Aug 2007, Benjamin Arai wrote:
So, I built my tables which contains a TSearch2 field by
1. Create table without indexes
2. COPY data into table
3. ALTER TABLE tblMessages ADD COLUMN idxFTI tsvector;
4. UPDATE tblMessages SET idxFTI=to_tsvector('default',
strMessage);
Or you could set up a trigger to generate the tsvector when you first
load the data instead of adding it later.
You're going to want such a trigger anyway, so installing it before
the
COPY step seems like the Obviously Right Thing. Any other approach
implies rewriting the entire table after you've loaded it, with no
compensating advantage that I can see.
regards, tom lane
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