Hi, There are two areas: data de-duplication, and data compression.
** Data De-Duplication ** For BLOB and CLOB, data de-duplication is used for version 1.3.x, but only up to some point. Version 1.4.x does not use it, as it deceases write performance, and only helps for fairly small databases. For version 1.4.x, more work might be done in this area. There is standalone de-duplication + compression tool in the source tree: "A standalone archive tool to compress directories". See under src/tools, org.h2.dev.fs.ArchiveTool. ** Data Compression ** Version 1.3.x had BLOB / CLOB compression (individual entries were compressed). This helps for XML / HTML. Version 1.4.x has tabular data compression, which includes BLOB / CLOB but also regular tables an indexes. Append ";compress=true" to the database URL to use it. See http://h2database.com/javadoc/org/h2/engine/DbSettings.html#COMPRESS and http://h2database.com/javadoc/org/h2/engine/DbSettings.html . Regards, Thomas On Tue, Jul 8, 2014 at 8:38 AM, Ryan How <[email protected]> wrote: > I thought it did this already? > > It just saves the string once and uses the hash or something? > > I can't find it, but I thought I read such a thing in my years or forum > browsing on here... It was like an internal de-duplication that happened by > default. Maybe I was dreaming... > > Ryan > > > > On 8/07/2014 2:34 PM, Noel Grandin wrote: > > No, we don't have such a feature. > > You can enable compression on a database-wide basis, but not per-table. > > On 2014-07-08 01:14 AM, gaurav wrote: > > Is there any option to reduce space usage for varchar type columns when > the values for some of the columns may be > repeated, below is an example dataset: > > > > -- > You received this message because you are subscribed to the Google Groups > "H2 Database" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/h2-database. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "H2 Database" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/h2-database. For more options, visit https://groups.google.com/d/optout.
