chore(ET-6463): add large object snapshot doc

product_docs/docs/edb-postgres-ai/innovation-release/hybrid-manager/using_hybrid_manager/migration/dms_agent_reference.mdx

@@ -151,6 +151,106 @@ Oracle examples:
 - Disable network encryption negotiation: `oracle.net.encryption_client=REJECTED`
 - Set session program name: `v$session.program=DMSAgent`
 
+## Postgres Large object migration parameters
+
+### LO_SNAPSHOT_ENABLED
+
+Feature gate for the large object snapshot. When false (the default), no large object related
+operations run: the source is not scanned, no partitions are computed, and nothing is uploaded
+or published. Set to true to opt into the large object snapshot.
+
+### LO_SNAPSHOT_PARALLELISM
+
+Number of parallel workers used for the large object snapshot. 
+
+For example the LO_SNAPSHOT_PARALLELISM = 20
+
+If the agent mode is reader, there will be 20 workers COPY OUT the large object from source database and upload to object storage in parallel.
+
+If the agent mode is writer, there will be 20 workers download the large object and COPY IN to the target database.
+
+#### Recommandation:
+
+**Our performance benchmark test environment setting:**
+
+Deploy Source postgres database(8vCPU, 32G Mem) and Reader mode agent(16vCPU, 16G Mem) in one i4i.8xlarge EC2
+
+Deploy Target epas database(16vCPU, 32G Mem) and Writer mode agent(4vCPU, 16G Mem) in another one i4i.8xlarge EC2
+
+**Tables setting:**
+
+Large objects counts: 6400
+
+Large objects size: 32MB
+
+Large objects expected partion size: 1024MB
+
+Forign key paraent table size: 100000rows
+
+Forign key child table size: 10000000rows
+
+Integer Non-unique index size: 10000000rows
+
+**Large object agent setting:**
+
+Reader mode agent parallelism: 24
+
+Writer mode agent parallelism: 32
+
+**How to calculate large object snapshot duration:**
+
+Search log in reader mode agent:
+```
+T1: 2026-08-27 06:25:44,632 INFO  [com.enterprisedb.transporter.cdcreader.largeobject.LargeObjectManager] (pool-11-thread-1) [LO snapshot] Start large object snapshot
+T2: 2026-08-27 06:26:14,491 INFO  [com.enterprisedb.transporter.cdcreader.largeobject.LargeObjectManager] (pool-11-thread-1) [LO snapshot] Published large object manifest completion for topic org_beaconator4Appli_prj_xGQSUwMKDJZCxvhx.67590cea-a1df-11f1-a5fa-f66ef5321c73.large-object-manifest (partitionCount=16)
+```
+calculte the large object COPY OUT and upload time = T2 - T1
+
+Search log in writer mode agent:
+```
+T3: 2026-08-27 06:25:44,725 INFO  [com.enterprisedb.transporter.cdcwriter.connector.Connector] (pool-9-thread-1) [LO snapshot] Launching large object manifest consumer for edb
+T4: 2026-08-27 06:26:59,315 INFO  [com.enterprisedb.transporter.cdcwriter.connector.Connector] (lo-manifest-consumer-edb) [LO snapshot] Large object snapshot finished for edb
+```
+calculte the end to end time = T4 - T1 
+
+**Result:**
+
+| E2E duration | Speed (MB/s) | Reader Peak CPU | Reader Peak Mem | Writer Peak CPU | Writer Peak Mem | Source Peak CPU | Source Peak Mem | Target Peak CPU | Target Peak Mem |
+|--------------|--------------|-----------------|-----------------|-----------------|-----------------|-----------------|-----------------|-----------------|-----------------|
+| 8min30s      | 401.57       | 47.90%          | 35.10%          | 49%             | 12.80%          | 38%             | 75.10%          | 39.50%          | 25%             |
+
+### LO_SNAPSHOT_PARTITION_TARGET_MB
+
+All the large object will be splited to different partition. This option is the your expected partion size in MB.
+
+### LO_SNAPSHOT_PARTITION_TARGET_LO_COUNT
+
+All the large object will be splited to different partition. This option is the your expected large object count for each partion.
+Agent will compute the partition number using both LO_SNAPSHOT_PARTITION_TARGET_MB and LO_SNAPSHOT_PARTITION_TARGET_LO_COUNT then 
+chose the larger one.
+
+### LO_SNAPSHOT_COMPRESSION_RATIO
+
+Compression ratio used to estimate logical (decompressed) volume. Intentionally unset by default:
+when empty, the logical volume is estimated by sampling large objects at startup. When pinned, the
+value is used directly with no sampling.
+
+### LO_SNAPSHOT_SAMPLE_LO_COUNT
+
+Number of large objects to decompress when estimating the compression ratio. A fixed count
+(not a percentage) bounds the sampling cost regardless of total LO volume (default: 200)
+Larger LO_SNAPSHOT_SAMPLE_LO_COUNT will increase the estimating time.
+
+### LO_SNAPSHOT_SAMPLE_TIMEOUT_SECONDS
+
+Statement timeout (seconds) for the sampling query for estimating the compression ratio (default: 30)
+Increase this when agnet timeout during estimating the compression ratio 
+
+### LO_SNAPSHOT_HIGH_VOLUME_WARN_LOGICAL_GB
+
+Estimated logical (decompressed) large object volume, in GiB, at or above which the snapshot logs a
+high-volume WARN at startup. Set to 0 to disable the warning (default: 5120)
+
 ## Optional parameters
 
 ### METRICS_TASK_ENABLED