The Filter syntax element specifies filters to impose on the matched rows. Filtering out most matches can improve performance, but memory fragmentation can degrade it. Memory fragmentation can occur in these cases:
- The mode is NONOVERLAPPING and the pattern includes the end anchor operator ($) but not the start anchor operator (^).
- The mode is OVERLAPPING and the pattern does not include the start anchor operator.
- The first symbol in the pattern can match an infinite number of input rows.
- The data partition is huge.
- The Java Virtual Machine (JVM) is too small.
If nPath runs much slower with the Filter syntax element, increase the size of the JVM. If the problem persists, alter the pattern.