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| author | A. Jesse Jiryu Davis <jesse@mongodb.com> | 2020-10-05 13:06:52 -0400 |
|---|---|---|
| committer | Evergreen Agent <no-reply@evergreen.mongodb.com> | 2020-10-05 17:25:52 +0000 |
| commit | 03b9dce2762f3ebc8989f9802f982eb7e855a2be (patch) | |
| tree | f607abad85d62378f9699cb8fcd69764bb5fbbe5 /src/mongo/db/repl/README.md | |
| parent | 6427e5fdafc0ceac7caeee1bc455f9fb94bba131 (diff) | |
| download | mongo-03b9dce2762f3ebc8989f9802f982eb7e855a2be.tar.gz | |
SERVER-49929 Describe system collections in arch guide
Diffstat (limited to 'src/mongo/db/repl/README.md')
| -rw-r--r-- | src/mongo/db/repl/README.md | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/src/mongo/db/repl/README.md b/src/mongo/db/repl/README.md index 58370de7a2f..89396034892 100644 --- a/src/mongo/db/repl/README.md +++ b/src/mongo/db/repl/README.md @@ -1879,6 +1879,14 @@ is updated to reflect the new upgraded or downgraded state. This update is also `writeConcern: majority`. The new in-memory FCV value will be updated to reflect the on-disk changes. +# System Collections + +Much of mongod's configuration and state is persisted in "system collections" in the "admin" +database, such as `admin.system.version`, or the "config" database, such as `config.transactions`. +(These collections are both replicated. Unreplicated configuration and state is stored in the +"local" database.) The difference between "admin" and "config" for system collections is historical; +from now on when we invent a new system collection we will place it on "admin". + # Replication Timestamp Glossary In this section, when we refer to the word "transaction" without any other qualifier, we are talking @@ -1999,4 +2007,4 @@ entire node which can result in longer periods of write unavailability for the r The PrimaryOnlyService interface is more sophisticated than the ReplicaSetAwareService interface and is designed specifically for services built on persistent state machines that must be driven to conclusion by the Primary node of the replica set, even across failovers. Check out [this -document](../../../../docs/primary_only_service.md) for more information about PrimaryOnlyServices.
\ No newline at end of file +document](../../../../docs/primary_only_service.md) for more information about PrimaryOnlyServices. |