[docs] CDC: Documentation updates for CDC

docs/content/preview/explore/change-data-capture/using-logical-replication/_index.md

@@ -112,3 +112,5 @@ For reference documentation, see [YugabyteDB Connector](./yugabytedb-connector/)
 - Support for transaction savepoints is tracked in issue [10936](https://github.com/yugabyte/yugabyte-db/issues/10936).
 
 - Support for enabling CDC on Read Replicas is tracked in issue [11116](https://github.com/yugabyte/yugabyte-db/issues/11116).
+
+- Support for tablet splitting with logical replication is disabled from YB version 2024.1.4 & 2024.2.1. It is tracked in issue [24918](https://github.com/yugabyte/yugabyte-db/issues/24918).

docs/content/preview/explore/change-data-capture/using-logical-replication/monitor.md

@@ -80,6 +80,12 @@ Provide information about CDC service in YugabyteDB.
 | cdcsdk_sent_lag_micros | `long` | The LAG metric is calculated by subtracting the timestamp of the latest record in the WAL of a tablet from the last record sent to the CDC connector. |
 | cdcsdk_expiry_time_ms | `long` | The time left to read records from WAL is tracked by the Stream Expiry Time (ms). |
 
+{{< note title="Note">}}
+
+The cdc service metrics are calculated for every tablet that is of interest for a replication slot. In the scenario where user is not interested in polling all the tables (and consequently all the tablets) in database, the metrics will be calculated considering the unpolled tablets until [cdcsdk_tablet_not_of_interest_timeout_secs](../../../reference/configuration/yb-tserver/#cdcsdk-tablet-not-of-interest-timeout-secs) interval.
+
+{{< /note >}}
+
 ## Connector metrics
 
 <!-- TODO (Siddharth): Fix link to connector metrics section -->

docs/content/preview/explore/change-data-capture/using-logical-replication/yugabytedb-connector.md

@@ -352,7 +352,7 @@ There are 4 possible values for `REPLICA IDENTITY`:
 
 {{< note title="Note">}}
 
-YugabyteDB supports the replica identity CHANGE only with the plugin `yboutput`.
+The plugin `pgoutput` does not support replica identity CHANGE.
 
 {{< /note >}}
 
@@ -1095,6 +1095,10 @@ YugabyteDB connector events are designed to work with [Kafka log compaction](htt
 
 When a row is deleted, the _delete_ event value still works with log compaction, because Kafka can remove all earlier messages that have that same key. However, for Kafka to remove all messages that have that same key, the message value must be `null`. To make this possible, the YugabyteDB connector follows a _delete_ event with a special tombstone event that has the same key but a `null` value.
 
+## Updating or deleting a row which was inserted in the same transaction
+
+If a row is updated or deleted in the same transaction in which it was inserted, CDC cannot retrieve the before-image values for the UPDATE / DELETE event. If the replica identity is not `CHANGE` then CDC will throw an error while processing such events. To handle such updates/deletes with a non-CHANGE replica identity, set the tserver flag [cdc_send_null_before_image_if_not_exists](../../../reference/configuration/yb-tserver/#cdc-send-null-before-image-if-not-exists) to true. With this flag enabled, CDC will send a null before-image instead of failing with an error.
+
 <!-- YB Note skipping content for truncate and message events -->
 
 ## Data type mappings

docs/content/preview/explore/change-data-capture/using-yugabytedb-grpc-replication/_index.md

@@ -57,7 +57,7 @@ For reference documentation, see [YugabyteDB gRPC Connector](./debezium-connecto
 
 * A single stream can only be used to stream data from one namespace only.
 * There should be a primary key on the table you want to stream the changes from.
-* CDC is not supported on a target table for xCluster replication [11829](https://github.com/yugabyte/yugabyte-db/issues/11829).
+* CDC is not supported on tables (both source and target) for xCluster replication [25371](https://github.com/yugabyte/yugabyte-db/issues/25371) and [15534](https://github.com/yugabyte/yugabyte-db/issues/15534).
 * Currently, CDC doesn't support schema evolution for changes that require table rewrites (for example, [ALTER TYPE](../../../api/ysql/the-sql-language/statements/ddl_alter_table/#alter-type-with-table-rewrite)), or DROP TABLE and TRUNCATE TABLE operations.
 * YCQL tables aren't currently supported. Issue [11320](https://github.com/yugabyte/yugabyte-db/issues/11320).
 * [Composite types](../../ysql-language-features/data-types#composite-types) are currently not supported. Issue [25221](https://github.com/yugabyte/yugabyte-db/issues/25221).

docs/content/preview/explore/change-data-capture/using-yugabytedb-grpc-replication/cdc-get-started.md

@@ -433,6 +433,10 @@ For record type `MODIFIED_COLUMNS_OLD_AND_NEW_IMAGES`, the update and delete rec
 
 </td> </tr> </table>
 
+### Updating or deleting a row which was inserted in the same transaction
+
+If a row is updated or deleted in the same transaction in which it was inserted, CDC cannot retrieve the before-image values for the UPDATE / DELETE event. If the before image record type is not `CHANGE` then CDC will throw an error while processing such events. To handle such updates/deletes with a non-CHANGE before image record type, set the tserver flag [cdc_send_null_before_image_if_not_exists](../../../reference/configuration/yb-tserver/#cdc-send-null-before-image-if-not-exists) to true. With this flag enabled, CDC will send a null before-image instead of failing with an error.
+
 ## Schema evolution
 
 Table schema is needed for decoding and processing the changes and populating CDC records. Thus, older schemas are retained if CDC streams are lagging. Also, older schemas that are not needed for any of the existing active CDC streams are garbage collected. In addition, if before image is enabled, the schema needed for populating before image is also retained. The YugabyteDB source connector caches schema at the tablet level. This means that for every tablet the connector has a copy of the current schema for the tablet it is polling the changes for. As soon as a DDL command is executed on the source table, the CDC service emits a record with the new schema for all the tablets. The YugabyteDB source connector then reads those records and modifies its cached schema gracefully.

docs/content/preview/explore/change-data-capture/using-yugabytedb-grpc-replication/cdc-monitor.md

@@ -81,6 +81,12 @@ Provide information about CDC service in YugabyteDB.
 | cdcsdk_sent_lag_micros | `long` | The LAG metric is calculated by subtracting the timestamp of the latest record in the WAL of a tablet from the last record sent to the CDC connector. |
 | cdcsdk_expiry_time_ms | `long` | The time left to read records from WAL is tracked by the Stream Expiry Time (ms). |
 
+{{< note title="Note">}}
+
+The cdc service metrics are calculated for every tablet that is of interest for a particular stream. In the scenario where user is not interested in polling all the tables (and consequently all the tablets) in database, the metrics will be calculated considering the unpolled tablets until [cdcsdk_tablet_not_of_interest_timeout_secs](../../../reference/configuration/yb-tserver/#cdcsdk-tablet-not-of-interest-timeout-secs) interval.
+
+{{< /note >}}
+
 ### Snapshot metrics
 
 The **MBean** is `debezium.yugabytedb:type=connector-metrics,server=<database.server.name>,task=<task.id>,context=snapshot`.

docs/content/preview/reference/configuration/yb-tserver.md

@@ -1374,6 +1374,18 @@ Determines the window in milliseconds in which if a client has consumed the chan
 
 Default: `60000`
 
+##### --cdc_send_null_before_image_if_not_exists
+
+When this flag is set to true, CDC service will return a null before image if it is not able to find one.
+
+Default: `false`
+
+##### --cdcsdk_tablet_not_of_interest_timeout_secs
+
+Timeout after which it is inferred that a particular tablet is not of interest for CDC. Inorder to indicate that a particular tablet is of interest for CDC, it should be polled atleast once within this interval of stream / slot creation.
+
+Default: `14400 (4 hours)`
+
 ## File expiration based on TTL flags
 
 ##### --tablet_enable_ttl_file_filter

docs/content/stable/explore/change-data-capture/using-logical-replication/monitor.md

@@ -80,6 +80,12 @@ Provide information about CDC service in YugabyteDB.
 | cdcsdk_sent_lag_micros | `long` | The LAG metric is calculated by subtracting the timestamp of the latest record in the WAL of a tablet from the last record sent to the CDC connector. |
 | cdcsdk_expiry_time_ms | `long` | The time left to read records from WAL is tracked by the Stream Expiry Time (ms). |
 
+{{< note title="Note">}}
+
+The cdc service metrics are calculated for every tablet that is of interest for a replication slot. In the scenario where user is not interested in polling all the tables (and consequently all the tablets) in database, the metrics will be calculated considering the unpolled tablets until [cdcsdk_tablet_not_of_interest_timeout_secs](../../../reference/configuration/yb-tserver/#cdcsdk-tablet-not-of-interest-timeout-secs) interval.
+
+{{< /note >}}
+
 ## Connector metrics
 
 <!-- TODO (Siddharth): Fix link to connector metrics section -->

docs/content/stable/explore/change-data-capture/using-logical-replication/yugabytedb-connector.md

@@ -350,7 +350,7 @@ There are 4 possible values for `REPLICA IDENTITY`:
 
 {{< note title="Note">}}
 
-YugabyteDB supports the replica identity CHANGE only with the plugin `yboutput`.
+The plugin `pgoutput` does not support replica identity CHANGE.
 
 {{< /note >}}
 
@@ -1093,6 +1093,10 @@ YugabyteDB connector events are designed to work with [Kafka log compaction](htt
 
 When a row is deleted, the _delete_ event value still works with log compaction, because Kafka can remove all earlier messages that have that same key. However, for Kafka to remove all messages that have that same key, the message value must be `null`. To make this possible, the YugabyteDB connector follows a _delete_ event with a special tombstone event that has the same key but a `null` value.
 
+## Updating or deleting a row which was inserted in the same transaction
+
+If a row is updated or deleted in the same transaction in which it was inserted, CDC cannot retrieve the before-image values for the UPDATE / DELETE event. If the replica identity is not `CHANGE` then CDC will throw an error while processing such events. To handle such updates/deletes with a non-CHANGE replica identity, set the tserver flag [cdc_send_null_before_image_if_not_exists](../../../reference/configuration/yb-tserver/#cdc-send-null-before-image-if-not-exists) to true. With this flag enabled, CDC will send a null before-image instead of failing with an error.
+
 <!-- YB Note skipping content for truncate and message events -->
 
 ## Data type mappings

docs/content/stable/explore/change-data-capture/using-yugabytedb-grpc-replication/_index.md

@@ -55,7 +55,7 @@ For reference documentation, see [YugabyteDB gRPC Connector](./debezium-connecto
 
 * A single stream can only be used to stream data from one namespace only.
 * There should be a primary key on the table you want to stream the changes from.
-* CDC is not supported on a target table for xCluster replication [11829](https://github.com/yugabyte/yugabyte-db/issues/11829).
+* CDC is not supported on tables (both source and target) for xCluster replication [25371](https://github.com/yugabyte/yugabyte-db/issues/25371) and [15534](https://github.com/yugabyte/yugabyte-db/issues/15534).
 * Currently, CDC doesn't support schema evolution for changes that require table rewrites (for example, [ALTER TYPE](../../../api/ysql/the-sql-language/statements/ddl_alter_table/#alter-type-with-table-rewrite)), or DROP TABLE and TRUNCATE TABLE operations.
 * YCQL tables aren't currently supported. Issue [11320](https://github.com/yugabyte/yugabyte-db/issues/11320).
 

docs/content/stable/explore/change-data-capture/using-yugabytedb-grpc-replication/cdc-get-started.md

@@ -431,6 +431,10 @@ For record type `MODIFIED_COLUMNS_OLD_AND_NEW_IMAGES`, the update and delete rec
 
 </td> </tr> </table>
 
+### Updating or deleting a row which was inserted in the same transaction
+
+If a row is updated or deleted in the same transaction in which it was inserted, CDC cannot retrieve the before-image values for the UPDATE / DELETE event. If the before image record type is not `CHANGE` then CDC will throw an error while processing such events. To handle such updates/deletes with a non-CHANGE before image record type, set the tserver flag [cdc_send_null_before_image_if_not_exists](../../../reference/configuration/yb-tserver/#cdc-send-null-before-image-if-not-exists) to true. With this flag enabled, CDC will send a null before-image instead of failing with an error.
+
 ## Schema evolution
 
 Table schema is needed for decoding and processing the changes and populating CDC records. Thus, older schemas are retained if CDC streams are lagging. Also, older schemas that are not needed for any of the existing active CDC streams are garbage collected. In addition, if before image is enabled, the schema needed for populating before image is also retained. The YugabyteDB source connector caches schema at the tablet level. This means that for every tablet the connector has a copy of the current schema for the tablet it is polling the changes for. As soon as a DDL command is executed on the source table, the CDC service emits a record with the new schema for all the tablets. The YugabyteDB source connector then reads those records and modifies its cached schema gracefully.

docs/content/stable/explore/change-data-capture/using-yugabytedb-grpc-replication/cdc-monitor.md

@@ -79,6 +79,12 @@ Provide information about CDC service in YugabyteDB.
 | cdcsdk_sent_lag_micros | `long` | The LAG metric is calculated by subtracting the timestamp of the latest record in the WAL of a tablet from the last record sent to the CDC connector. |
 | cdcsdk_expiry_time_ms | `long` | The time left to read records from WAL is tracked by the Stream Expiry Time (ms). |
 
+{{< note title="Note">}}
+
+The cdc service metrics are calculated for every tablet that is of interest for a particular stream. In the scenario where user is not interested in polling all the tables (and consequently all the tablets) in database, the metrics will be calculated considering the unpolled tablets until [cdcsdk_tablet_not_of_interest_timeout_secs](../../../reference/configuration/yb-tserver/#cdcsdk-tablet-not-of-interest-timeout-secs) interval.
+
+{{< /note >}}
+
 ### Snapshot metrics
 
 The **MBean** is `debezium.yugabytedb:type=connector-metrics,server=<database.server.name>,task=<task.id>,context=snapshot`.

docs/content/stable/reference/configuration/yb-tserver.md

@@ -1382,6 +1382,18 @@ Determines the window in milliseconds in which if a client has consumed the chan
 
 Default: `60000`
 
+##### --cdc_send_null_before_image_if_not_exists
+
+When this flag is set to true, CDC service will return a null before image if it is not able to find one.
+
+Default: `false`
+
+##### --cdcsdk_tablet_not_of_interest_timeout_secs
+
+Timeout after which it is inferred that a particular tablet is not of interest for CDC. Inorder to indicate that a particular tablet is of interest for CDC, it should be polled atleast once within this interval of stream / slot creation.
+
+Default: `14400 (4 hours)`
+
 ## File expiration based on TTL flags
 
 ##### --tablet_enable_ttl_file_filter