If PDF is electronic paper, then pdftk is an electronic staple-remover, hole-punch, binder, secret-decoder-ring, and X-Ray-glasses. Pdftk is a simple tool for doing everyday things with PDF documents.
If the MERGE algorithm cannot be used, a temporary table must be used instead. MERGE cannot be used if the view contains any of the following constructs: * Aggregate functions (SUM(), MIN(), MAX(), COUNT(), and so forth) * DISTINCT * GROUP BY * HAVING * LIMIT * UNION or UNION ALL * Subquery in the select list * Refers only to literal values (in this case, there is no underlying table)
Subversion 1.5 will support Merge Tracking. This blog post provides a high level overview of what Merge Tracking is, why it is important and what it means to your organization.
H. chih Yang, A. Dasdan, R. Hsiao, и D. Parker. SIGMOD '07: Proceedings of the 2007 ACM SIGMOD international conference on Management of data, стр. 1029--1040. New York, NY, USA, ACM, (2007)