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| author | Bruce Momjian <bruce@momjian.us> | 2011-01-26 19:54:41 -0500 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2011-01-26 19:54:41 -0500 |
| commit | 81c48aeaa8fd34f90ab6d6f1d56564d34ac4aa59 (patch) | |
| tree | 317e645fd570dba3fe6dd792caec5565cf5ec9e9 | |
| parent | 7ab6f2da23516e48174f3f144ee9ef19bdc287fb (diff) | |
| download | postgresql-81c48aeaa8fd34f90ab6d6f1d56564d34ac4aa59.tar.gz postgresql-81c48aeaa8fd34f90ab6d6f1d56564d34ac4aa59.zip | |
Restructure streaming docs so streaming seems more integrated in the
paragraphs, per suggestion from Dan Birken.
| -rw-r--r-- | doc/src/sgml/high-availability.sgml | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml index 717347cc999..ce3f2642e86 100644 --- a/doc/src/sgml/high-availability.sgml +++ b/doc/src/sgml/high-availability.sgml @@ -486,18 +486,19 @@ protocol to make nodes agree on a serializable transactional order. <para> Directly moving WAL records from one database server to another is typically described as log shipping. <productname>PostgreSQL</> - implements file-based log shipping, which means that WAL records are - transferred one file (WAL segment) at a time. WAL files (16MB) can be + implements file-based log shipping by transfering WAL records + one file (WAL segment) at a time. WAL files (16MB) can be shipped easily and cheaply over any distance, whether it be to an adjacent system, another system at the same site, or another system on the far side of the globe. The bandwidth required for this technique varies according to the transaction rate of the primary server. - Record-based log shipping is also possible with streaming replication - (see <xref linkend="streaming-replication">). + Record-based log shipping is more granular and streams WAL changes + incrementally over a network connection (see <xref + linkend="streaming-replication">). </para> <para> - It should be noted that the log shipping is asynchronous, i.e., the WAL + It should be noted that log shipping is asynchronous, i.e., the WAL records are shipped after transaction commit. As a result, there is a window for data loss should the primary server suffer a catastrophic failure; transactions not yet shipped will be lost. The size of the @@ -505,8 +506,8 @@ protocol to make nodes agree on a serializable transactional order. <varname>archive_timeout</varname> parameter, which can be set as low as a few seconds. However such a low setting will substantially increase the bandwidth required for file shipping. - If you need a window of less than a minute or so, consider using - streaming replication (see <xref linkend="streaming-replication">). + Streaming replication (see <xref linkend="streaming-replication">) + allows a much smaller window of data loss. </para> <para> |