From 8c167930af17e3d57525e5a430a386befbc84dcf Mon Sep 17 00:00:00 2001 From: Dj Walker-Morgan Date: Tue, 29 Aug 2023 10:30:24 +0100 Subject: [PATCH] Brought out limitations Signed-off-by: Dj Walker-Morgan --- .../docs/pgd/5/durability/group-commit.mdx | 28 +---------------- product_docs/docs/pgd/5/durability/index.mdx | 4 +++ .../docs/pgd/5/durability/limitations.mdx | 31 +++++++++++++++++++ 3 files changed, 36 insertions(+), 27 deletions(-) create mode 100644 product_docs/docs/pgd/5/durability/limitations.mdx diff --git a/product_docs/docs/pgd/5/durability/group-commit.mdx b/product_docs/docs/pgd/5/durability/group-commit.mdx index 185eb7eda82..87c0fc5208c 100644 --- a/product_docs/docs/pgd/5/durability/group-commit.mdx +++ b/product_docs/docs/pgd/5/durability/group-commit.mdx @@ -76,30 +76,4 @@ transaction abort is requested. If the transaction is already decided to be committed at the time the abort request is sent, the transaction does eventually COMMIT even though the client might receive an abort message. -## Limitations - -Group Commit transactions can't yet execute DDL, -and they don't support explicit two-phase commit. Future releases might allow them. -However, the `TRUNCATE` command is allowed. - -You can combine only CAMO transactions with the `DEGRADE TO` clause for switching -to asynchronous operation in case of lowered availability. - -Eager and CAMO transactions aren't currently supported in combination -with the Decoding Worker feature or with transaction streaming. -Installations using Eager must keep `enable_wal_decoder` and `streaming_mode` -disabled for the PGD node group. - -Synchronous replication uses a mechanism for transaction confirmation -different from Group Commit. The two aren't compatible, and you must not use -them together. Therefore, whenever you Group Commit transactions, -make sure none of the PGD nodes are configured in -`synchronous_standby_names`. - -Currently, Raft commit decisions are extremely slow, producing very low TPS. We recommended -using them only with the `eager` conflict resolution setting -to get the Eager All-Node Replication behavior of PGD 4 and older. - -Combining different commit decision options in the same transaction isn't -supported. Combining different conflict resolution options in the same transaction also isn't -supported. +See also [Limitations](limitations). \ No newline at end of file diff --git a/product_docs/docs/pgd/5/durability/index.mdx b/product_docs/docs/pgd/5/durability/index.mdx index b103ba60017..96d30e45fe4 100644 --- a/product_docs/docs/pgd/5/durability/index.mdx +++ b/product_docs/docs/pgd/5/durability/index.mdx @@ -11,6 +11,7 @@ navigation: - lag-control - administering - legacy-sync + - limitations redirects: - /pgd/latest/bdr/durability/ @@ -49,6 +50,9 @@ in use should be managed. [Legacy Sync](legacy-sync) shows how traditional Postgres synchronous operations can still be accessed under EDB Postgres Distributed. +[Limitations](limitations) lists the various combinations of durability options +which are not currently supported or not possible. Do refer to this before deciding +on a durability strategy.