iffyio commented on code in PR #2352:
URL:
https://github.com/apache/datafusion-sqlparser-rs/pull/2352#discussion_r3311511688
##########
src/parser/mod.rs:
##########
@@ -1717,6 +1731,23 @@ impl<'a> Parser<'a> {
return prefix;
}
+ // Memoize parse_prefix failures to break 2^N speculation when both
+ // prefix arms fail at every level (e.g. `IF(current_time(...x`).
+ // The per-arm cache in `parse_prefix_inner` complements this for
+ // chains where the reserved arm fails but the unreserved fallback
+ // succeeds (e.g. `case-case-...c`).
+ let start_index = self.index;
+ if let Some(cached) = self.failed_prefix_positions.get(&start_index) {
+ return Err(cached.clone());
+ }
+ let result = self.parse_prefix_inner();
+ if let Err(ref e) = result {
+ self.failed_prefix_positions.insert(start_index, e.clone());
Review Comment:
hmm yeah I'm mostly worried about the increased memory usage. A lot of
deployments don't have e.g. 2GB to allocate to parsing a sql query. I think the
main issue is that the map contains strings, maybe if its a much cheaper/copy
object somehow we were looking to store, it might be feasible.
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