B V, Phanisekhar <[EMAIL PROTECTED]> wrote:
Why it's unpredictable?
You are enumerating rows in some order. A new row may be inserted before or after your current position in this order. If it is inserted before, you will not see it in this enumeration. If it is inserted after, you will eventually reach it.
With simple enough queries, you may guess (or explicitly specify wit ORDER BY) the order in which rows are enumerated, and can predict whether a newly inserted order will be seen. With complex queries, it may be difficult to make such a prediction.
In sqlite 3.3.8, since it allows INSERT while SELECT statement is running, I assume that it will return an 11th row. Can you explain how step operation works interiorly on a table?
It walks a B-Tree, moving from current node to the next.
(Does it gets all the results at one time
Not most of the time, but some queries require such a temporary intermediate resultset. E.g. a query with ORDER BY on a table that doesn't have a suitable index has no choice but to retrieve all records, sort them in a temporary resultset, then enumerate that resultset. In this case, by the way, a row inserted into the table in the middle of enumeration will not be seen.
or it searches for the rows matching the criteria one after the other
SQLite tries hard to do it this way, but for some queries it is not possible.
Igor Tandetnik
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