--- title: "FAQ" slug: "dev-database-troubleshooting-faq" description: "Learn essential steps for database setup, table choices, and transaction management in VAST, ensuring smooth data handling and integration." updated: 2026-10-30T18:18:46Z published: 2026-10-30T18:18:46Z canonical: "docs.vastdata.com/dev-database-troubleshooting-faq" --- > ## Documentation Index > Fetch the complete documentation index at: https://docs.vastdata.com/llms.txt > Use this file to discover all available pages before exploring further. # FAQ *Applies to VAST Cluster 5.5. Examples use the VAST DataBase Python SDK 2.1.0.* ## Getting started **What do I need from my platform team?** A database, an endpoint, an access key pair, and an identity policy with the right actions. [Setup prerequisites](/develop/docs/dev-database-operations-setup-prerequisites) has a checklist and a request you can copy. **Which SDK version should I install?** On a 5.5 cluster, install `vastdb` 2.1.0. Partitioned tables need it. [Versions](/develop/docs/dev-database-reference-versions#sdk-and-cluster) **Can I use the management (VMS) address as the endpoint?** No. Use the address of a virtual IP pool that serves the database. The management address fails with `UnsupportedServer`. [Errors](/develop/docs/dev-database-troubleshooting-errors#vastdbinternalunsupportedserver-url-is-not-a-vast-db-server-endpoint-server-header) **My policy grants `s3:Tabular*`, so why do I get `Forbidden` straight away?** The SDK's first call on a database also needs `s3:ListBucket`. [Setup prerequisites](/develop/docs/dev-database-operations-setup-prerequisites#actions-each-sdk-operation-needs) ## Tables and data **What's a database, in VAST terms?** A bucket on a Database-enabled view. It holds schemas, and schemas hold tables. [Concepts](/develop/docs/dev-database-concepts-index) **Should I use a sorted table, a partitioned table or a projection?** It depends on how you'll query the table, and most of these choices can't be undone. [Data modeling](/develop/docs/dev-database-guides-data-modeling) walks through the choice. [Limits](/develop/docs/dev-database-reference-limits#combining-table-structures) lists which structures can be combined. **Can I change a table's sort columns or partitioning later?** No. Both are fixed once they're set. [Limits](/develop/docs/dev-database-reference-limits#what-cant-be-changed-later) **Why can't I update a sort column or a partition column?** The cluster doesn't allow changing them after a row is inserted. Delete the row and insert it again. [Updates and deletes](/develop/docs/dev-database-guides-updates-and-deletes#columns-you-cant-update) **How do I load a lot of data without sending it through my client?** Put Parquet files in a bucket, then import them with `import_files()`. The cluster reads the files itself, so the data doesn't pass through your client. [Ingest](/develop/docs/dev-database-guides-ingest#import-parquet-files) **Do rows come back in order?** No. Sort on the client if you need an order. [Querying](/develop/docs/dev-database-guides-querying#anti-patterns) **Why don't I see rows I just inserted in `get_stats()`?** Statistics are updated in the background, not when you commit, so they can be behind for a while (minutes on sorted and partitioned tables). The rows themselves are there; count them with a query to check. [Monitoring](/develop/docs/dev-database-operations-monitoring-your-workload#table-statistics) ## Transactions **What happens if my code raises inside `with session.transaction()`?** The transaction rolls back, and nothing it wrote is kept. The one exception is `delete_partitions()`, which a rollback doesn't undo. [Transactions in practice](/develop/docs/dev-database-guides-transactions-in-practice#commit-and-rollback) **Two jobs write to the same table. What can go wrong?** If they change the same row or object, one of them gets a `Conflict` (`TabularWwc`). Retry the whole transaction. [Transactions in practice](/develop/docs/dev-database-guides-transactions-in-practice#conflicts-between-transactions) **Is `delete_partitions()` transactional?** No. You have to pass `allow_non_acid=True`, and a rollback doesn't undo it. [Updates and deletes](/develop/docs/dev-database-guides-updates-and-deletes#delete-whole-partitions) ## Other engines **Can Trino and the SDK use the same tables?** Yes. All clients work on the same tables. Once your SDK transaction commits, Trino can query the rows. [Overview](/develop/docs/dev-database-overview#how-you-access-it) **Which Trino version goes with my cluster?** See the compatibility table in [versions](/develop/docs/dev-database-reference-versions#trino). **What is the VAST Query Engine, and how do I reach it?** It runs SQL inside the cluster. You reach it through the VAST ADBC driver, and you need `s3:QueryEngine*`. [VAST Query Engine (ADBC)](/develop/docs/dev-database-integrations-adbc) ยท [SQL reference](/develop/docs/dev-database-reference-sql-index) ## Getting help **What should I include when I report a problem?** The error's `code`, `message`, `status` and `url`, your SDK and cluster versions, and the time it happened. Remove addresses and keys first. [Troubleshooting](/develop/docs/dev-database-troubleshooting-index#before-you-ask-for-help)