On Fri, Jan 20, 2012 at 3:39 PM, Julian Reschke <julian.resc...@gmx.de> wrote: > On 2012-01-20 15:22, Bart van der Schans wrote: >> >> Hi all, >> >> I was wondering about how the ConsistencyCheckerImpl fetches all the >> node ids. The first set of node ids is fetched with >> "pm.getAllNodeIds(null, NODESATONCE)" in the internalCheckConsistency >> method. All subsequent sets are fetched with "pm.getAllNodeIds(lastId, >> NODESATONCE)". >> >> In the BundleDbPersistenceManager the method >> getAllNodeIds(NodeId,maxCount) uses the "bundleSelectAllIdsSQL" if the >> first parameter is null otherwise the "bundleSelectAllIdsFromSQL" >> query. The "bundleSelectAllIdsSQL" query doesn't use ordering and the >> "bundleSelectAllIdsFromSQL" does. >> >> Now my question is the following: souldn't the "bundleSelectAllIdsSQL" >> also use an order clause to make sure the correct batch of node ids is >> fetched the first time? Or is that somehow implicitly guaranteed? > > > Good question. I was confused about that as well. I tried and stepped > through he code and everything seem to worked as advertised, so I stopped > worrying about it :-)
I think (at least on mysql) we're just lucky that the natural ordering is by NODE_ID: mysql> SELECT hex(NODE_ID) FROM VERSION_BUNDLE ORDER BY NODE_ID LIMIT 0,10; +----------------------------------+ | hex(NODE_ID) | +----------------------------------+ | 000005E87E6D402BA27CDF41E7999D8A | | 000007DC02CF48BA8FFEDA5F566A3A98 | | 00000C4A81744934B4F0CB55C9967378 | | 000016C9E4464C4FA7B6F4B9CF2F9903 | | 00001D5A1C6F4339B317BB436AA54431 | | 0000257D67AB4F1EA4DDEDB84BB13039 | | 00002C51F22145B89F59E882BB505036 | | 00002F2AFC2E4842863C360B68A36BDA | | 0000354F151945CEA953D62C922A4FAC | | 00003C0254C8471E8349C0B6F0DEFDC2 | +----------------------------------+ 10 rows in set (0.00 sec) mysql> SELECT hex(NODE_ID) FROM VERSION_BUNDLE LIMIT 0,10; +----------------------------------+ | hex(NODE_ID) | +----------------------------------+ | 000005E87E6D402BA27CDF41E7999D8A | | 000007DC02CF48BA8FFEDA5F566A3A98 | | 00000C4A81744934B4F0CB55C9967378 | | 000016C9E4464C4FA7B6F4B9CF2F9903 | | 00001D5A1C6F4339B317BB436AA54431 | | 0000257D67AB4F1EA4DDEDB84BB13039 | | 00002C51F22145B89F59E882BB505036 | | 00002F2AFC2E4842863C360B68A36BDA | | 0000354F151945CEA953D62C922A4FAC | | 00003C0254C8471E8349C0B6F0DEFDC2 | +----------------------------------+ 10 rows in set (0.00 sec) But that doesn't have to be the case with other databases. Maybe somebody can try similar queries on another database? Regards, bart
