Learn XQuery

Summary

DataDirect XQuery® was designed for performance and scalability. It does sophisticated query optimization, supports prepared queries and query pooling, and efficiently queries large XML documents using document projection and streaming. If you follow these few simple guidelines, your DataDirect XQuery® applications will usually have good performance:

Prepare your queries, or use query pooling.
Use fn:doc() when possible for XML input; avoid parsing XML input yourself.
For large XML files, avoid wildcards ('*'), and use specific paths.
For large XML files, consider streaming if memory usage is large and performance is unsatisfactory.
Use SAX, StAX, or output streams for output; avoid using the DOM for output.
Avoid compensation in WHERE clauses and predicates.
Avoid AT clauses in FLWOR expressions that query relational tables.
Avoid numeric predicates in expressions that operate on relational data.
For shallow hierarchies, consider specifying a SQL generation algorithm.

Prev: "Specifying SQL Generation Algorithms"

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