docs: add a note about different hasura instances connecting to the same database

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/4637
Co-authored-by: Rikin Kachhia <54616969+rikinsk@users.noreply.github.com>
GitOrigin-RevId: b564f1037a5e31c7085c2b6aa5a364aa4a4e5c78
This commit is contained in:
Tirumarai Selvan 2022-06-06 15:45:20 +05:30 committed by hasura-bot
parent 524819b4b7
commit 2c8452396f
2 changed files with 19 additions and 2 deletions

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@ -121,3 +121,12 @@ with Heroku from inside of Hasura Cloud. For more information, see
[Connect new/existing database on Hasura Cloud](/graphql/cloud/getting-started/index.mdx#create-new-db-with-cloud).
:::
:::caution Connecting different Hasura instances to the same database
You can connect different Hasura instances (i.e. instances with different metadata) to the same database as long as
there are no Event Triggers in any of the metadata. Event Triggers store their data in the underlying database and
hence different instances acting on the same data can cause undefined behaviour during run-time.
This should not be a problem if the Hasura instances have the same metadata.
:::

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@ -13,7 +13,7 @@ import Thumbnail from "@site/src/components/Thumbnail";
## Introduction
Hasura can be used to create event triggers on tables in the Postgres database. Event triggers reliably capture events on specified tables and invoke webhooks to carry out any custom logic.
Hasura can be used to create event triggers on tables in the database. Event triggers reliably capture events on specified tables and invoke HTTP webhooks to carry out any custom logic.
<Thumbnail
src="/img/graphql/core/event-triggers/data-triggers-arch.png"
@ -32,7 +32,15 @@ Events can be of the following types:
:::info Note
Event webhook notifications will be delivered at least once, and may arrive out of order with respect to the underlying event.
- Event triggers are supported for **Postgres and MS SQL Server** databases.
- Event webhook notifications will be delivered at least once, and may arrive out of order with respect to the underlying event.
:::
:::caution Caveat on different Hasura instances connected to the same database
Event Triggers store their data in the underlying database and hence different instances acting on the same data can cause
undefined behaviour during run-time. This should not be a problem if the Hasura instances have the same metadata.
:::