Re: Slowdown problem when writing 1.7million records

> "Stephen Livesey" <ste@exact3ex.co.uk> writes:
> >> Further question --- is there any particular pattern to the order in
> >> which you are inserting the records?  For example, are they in order
> >> by postcode, or approximately so?
> >
> > Yes they would be inserted in postcode order.
>
> Ah.  What must be happening is that the index on postcode is getting
> badly misbalanced --- instead of a roughly symmetrical b-tree, all the
> branches link to the right, causing index insertions and lookups to scan
> the whole index instead of only an O(log N) portion of it.  You'd get
> better results if you inserted the data in random order, or dropped the
> index while inserting the data and then recreated it after the bulk
> loading is done.
>
> I am not sure how difficult this behavior might be to change, but in any
> case I'm not going to risk twiddling the btree code at this late stage
> of the 7.1 release cycle.  Bruce, would you add a TODO item?
>
> * Be smarter about insertion of already-ordered data into btree index

Added.  I thought our btree code was self-balancing.

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