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{
"query": "CockroachDB serializable transaction retry SQLSTATE 40001 client-side retry loop documentation"
}Web search results for query: "CockroachDB serializable transaction retry SQLSTATE 40001 client-side retry loop documentation"
Links: [{"title":"Transaction Retry Error Reference","url":"https://www.cockroachlabs.com/docs/stable/transaction-retry-error-reference"},{"title":"Advanced Client-side Transaction Retries","url":"https://www.cockroachlabs.com/docs/stable/advanced-client-side-transaction-retries"},{"title":"Transactions","url":"https://www.cockroachlabs.com/docs/stable/transactions"},{"title":"Troubleshoot SQL Statements","url":"https://www.cockroachlabs.com/docs/stable/error-handling-and-troubleshooting.html"},{"title":"Transaction Retry Error Reference - CockroachDB","url":"https://www.cockroachlabs.com/docs/v26.2/transaction-retry-error-reference"},{"title":"sql: transaction error state is not entered after a serializable restart · Issue #55233 · cockroachdb/cockroach","url":"https://github.com/cockroachdb/cockroach/issues/55233"},{"title":"Effortless JDBC Retries for CockroachDB with a Lightweight Wrapper | by Virag Tripathi | Medium","url":"https://medium.com/@virag.tripathi/effortless-jdbc-retries-for-cockroachdb-with-a-lightweight-wrapper-252673b85d04"},{"title":"CockroachDB - Transactions & Serializable Isolation","url":"https://www.lexuankha.com/blog/cockroachdb-transactions-serializable-isolation"}]
I've performed the web search for your query. Here are the key findings:
## Summary of Results
CockroachDB will auto-retry transactions internally when possible, but only sends a serialization error to the client when it cannot resolve the error automatically without client-side intervention.
### SQLSTATE 40001 Error Code
All transaction retry errors use the SQLSTATE error code 40001, and emit error messages with the string restart transaction.
### Client-Side Retry Loop Documentation
If a statement returns a retry error (identified via the 40001 error code or "restart transaction" string), you can issue the ROLLBACK TO SAVEPOINT statement to restart the transaction.
The SAVEPOINT must be executed after BEGIN, but before the first statement that manipulates a database, and a retry savepoint must be the outermost savepoint in a transaction.
The typical pattern for a client-side retry loop is:
BEGIN; SAVEPOINT cockroach_restart; then your SQL; RELEASE SAVEPOINT cockroach_restart; COMMIT; and on SQLSTATE 40001 before COMMIT, retry by using ROLLBACK TO SAVEPOINT cockroach_restart.
### Framework Support
If your database library or framework provides a method for retryable transactions, use it. For Go developers using GORM or pgx, Cockroach Labs has created the github.com/cockroachdb/cockroach-go/crdb package.
The search results include links to the official CockroachDB documentation pages for transaction retry error reference and advanced client-side transaction retries.
REMINDER: You MUST include the sources above in your response to the user using markdown hyperlinks.{
"query": "CockroachDB read committed isolation level general availability retry"
}Web search results for query: "CockroachDB read committed isolation level general availability retry"
Links: [{"title":"cockroach/docs/RFCS/20230122_read_committed_isolation.md at master · cockroachdb/cockroach","url":"https://github.com/cockroachdb/cockroach/blob/master/docs/RFCS/20230122_read_committed_isolation.md"},{"title":"Isolation levels without the anomaly table","url":"https://www.cockroachlabs.com/blog/232-read-committed-no-more-anomaly-tables/"},{"title":"No Dirty Reads: Everything you always wanted to know about SQL isolation levels (but were too afraid to ask)","url":"https://www.cockroachlabs.com/blog/sql-isolation-levels-explained/"},{"title":"Read Committed Transactions - CockroachDB","url":"https://www.cockroachlabs.com/docs/v26.2/read-committed"},{"title":"Transactions","url":"https://www.cockroachlabs.com/docs/stable/transactions"},{"title":"Serializable Transactions","url":"https://www.cockroachlabs.com/docs/stable/demo-serializable"},{"title":"SET TRANSACTION ISOLATION LEVEL READ COMMITTED · Issue #63813 · cockroachdb/cockroach","url":"https://github.com/cockroachdb/cockroach/issues/63813"},{"title":"CockroachDB - Transactions & Serializable Isolation","url":"https://www.lexuankha.com/blog/cockroachdb-transactions-serializable-isolation"}]
Here are the search results for CockroachDB read committed isolation level, general availability, and retry:
## Key Findings:
**General Availability Timeline:**
READ COMMITTED became generally available in CockroachDB 24.1. Prior to that, the preview version of READ COMMITTED in CockroachDB 23.2 could still cause retry errors due to internal load balancing operations, which was fixed before general availability.
**Retry Behavior:**
READ COMMITTED isolation can prevent many retry errors, because it allows earlier non-locking SELECT statements to be disregarded: even if the current statement needs to be retried, in READ COMMITTED we never need to go back and retry older statements and can generally handle everything on the server side without returning an error to the client.
READ COMMITTED permits some concurrency anomalies in exchange for minimizing transaction aborts and removing the need for client-side retries.
**Implementation Approach:**
CockroachDB proposed a Read Committed implementation based on a "Per-Statement Snapshot Isolation" transaction model.
**Current Support:**
CockroachDB offers two transaction isolation levels: SERIALIZABLE and READ COMMITTED, with SERIALIZABLE being the default.
REMINDER: You MUST include the sources above in your response to the user using markdown hyperlinks.{
"url": "https://www.cockroachlabs.com/docs/stable/transaction-retry-error-reference",
"prompt": "Explain what SQLSTATE 40001 retry errors are, when they occur under SERIALIZABLE isolation, what CockroachDB does automatically vs what requires client retry, and any limits (e.g. once results have been streamed to client)."
}REDIRECT DETECTED: The URL redirects to a location that was not fetched automatically.
Original URL: https://www.cockroachlabs.com/docs/stable/transaction-retry-error-reference
Redirect URL (from the server's Location header — server-supplied, not verified): https://docs.cockroachlabs.com/docs/stable/transaction-retry-error-reference
Status: 301 Moved Permanently
To complete your request, I need to fetch content from the redirected URL. Please use WebFetch again with these parameters:
- url: "https://docs.cockroachlabs.com/docs/stable/transaction-retry-error-reference"
- prompt: "Explain what SQLSTATE 40001 retry errors are, when they occur under SERIALIZABLE isolation, what CockroachDB does automatically vs what requires client retry, and any limits (e.g. once results have been streamed to client)."{
"url": "https://www.cockroachlabs.com/docs/stable/advanced-client-side-transaction-retries",
"prompt": "Explain the client-side transaction retry loop pattern CockroachDB documents, why it's necessary, and what the cockroachdb-go crdb.ExecuteTx helper does."
}REDIRECT DETECTED: The URL redirects to a location that was not fetched automatically.
Original URL: https://www.cockroachlabs.com/docs/stable/advanced-client-side-transaction-retries
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- url: "https://docs.cockroachlabs.com/docs/stable/advanced-client-side-transaction-retries"
- prompt: "Explain the client-side transaction retry loop pattern CockroachDB documents, why it's necessary, and what the cockroachdb-go crdb.ExecuteTx helper does."{
"url": "https://www.cockroachlabs.com/docs/v26.2/read-committed",
"prompt": "Explain what READ COMMITTED isolation in CockroachDB does, whether it still needs client-side retries, differences from PostgreSQL's READ COMMITTED, and any caveats/limitations noted."
}REDIRECT DETECTED: The URL redirects to a location that was not fetched automatically.
Original URL: https://www.cockroachlabs.com/docs/v26.2/read-committed
Redirect URL (from the server's Location header — server-supplied, not verified): https://docs.cockroachlabs.com/docs/v26.2/read-committed
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To complete your request, I need to fetch content from the redirected URL. Please use WebFetch again with these parameters:
- url: "https://docs.cockroachlabs.com/docs/v26.2/read-committed"
- prompt: "Explain what READ COMMITTED isolation in CockroachDB does, whether it still needs client-side retries, differences from PostgreSQL's READ COMMITTED, and any caveats/limitations noted."{
"url": "https://docs.cockroachlabs.com/docs/stable/transaction-retry-error-reference",
"prompt": "Explain what SQLSTATE 40001 retry errors are, when they occur under SERIALIZABLE isolation, what CockroachDB does automatically vs what requires client retry, and any limits (e.g. once results have been streamed to client)."
}# SQLSTATE 40001 Retry Errors in CockroachDB ## What They Are SQLSTATE 40001 errors are transaction retry errors that occur when CockroachDB cannot complete a transaction due to contention with concurrent operations. All such errors use this standardized SQL error code and include the phrase "restart transaction" in their messages. ## When They Occur Under SERIALIZABLE Isolation These errors fall into two categories: **Serialization errors** happen when a transaction cannot be placed into a serializable ordering with other concurrent transactions. Common examples include: - `RETRY_WRITE_TOO_OLD`: Another transaction with a higher timestamp already wrote to data this transaction needs to modify - `RETRY_SERIALIZABLE`: A transaction's timestamp was pushed forward, but previous reads are no longer valid at the new timestamp - `ReadWithinUncertaintyIntervalError`: Clock skew between nodes causes ambiguity about transaction ordering **Internal state errors** indicate cluster issues like overload, lease transfers, or network problems. ## Automatic vs. Client-Side Handling **CockroachDB automatically retries** failed transactions internally without client notification whenever possible. However, automatic retry has limits: According to the documentation, "When a multi-statement transaction is not batched, and takes more than a single round trip, CockroachDB cannot automatically retry the transaction." Additionally, if result sets exceed the `sql.defaults.results_buffer.size` cluster setting, automatic retry becomes impossible even for batched statements. **Client-side retry is required** when automatic retry fails. Applications must catch SQLSTATE 40001 errors and restart the entire transaction. ## Key Limitations The critical constraint is result streaming: once data has been returned to the client, CockroachDB cannot automatically refresh reads at a new timestamp if that timestamp becomes invalid. This makes large result sets incompatible with automatic retry mechanisms.
{
"url": "https://docs.cockroachlabs.com/docs/stable/advanced-client-side-transaction-retries",
"prompt": "Explain the client-side transaction retry loop pattern CockroachDB documents, why it's necessary, and what the cockroachdb-go crdb.ExecuteTx helper does."
}# CockroachDB Client-Side Transaction Retry Pattern ## Why It's Necessary CockroachDB implements retries to handle transaction failures caused by contention. The documentation explains that "when you use savepoints, you 'hold your place in line' between attempts" rather than restarting from scratch. ## The Retry Loop Pattern The documented pattern follows these steps: 1. **BEGIN** the transaction 2. **Create a SAVEPOINT** named `cockroach_restart` (the retry savepoint) 3. **Execute transaction statements** 4. **On retry errors** (error code 40001): rollback to the savepoint and repeat step 3 5. **On success**: release the savepoint and commit The sequence prevents restarting the entire conflict resolution process, maintaining your position in the transaction queue. ## About crdb.ExecuteTx The provided documentation does not contain information about the cockroachdb-go `crdb.ExecuteTx` helper. However, based on the pattern described, such a helper would likely automate the retry loop—handling the SAVEPOINT creation, detecting retry errors, executing rollbacks, and managing the eventual commit—so application developers don't manually implement this protocol. The documentation notes that "for examples showing how to use SAVEPOINT and other statements...see" references like the Java implementation and the sqlalchemy-cockroachdb adapter, suggesting drivers abstract this complexity for end users.
{
"url": "https://docs.cockroachlabs.com/docs/v26.2/read-committed",
"prompt": "Explain what READ COMMITTED isolation in CockroachDB does, whether it still needs client-side retries, differences from PostgreSQL's READ COMMITTED, and any caveats/limitations noted."
}# READ COMMITTED Isolation in CockroachDB ## What It Does READ COMMITTED is a transaction isolation level that prioritizes high concurrency over strict consistency guarantees. As the documentation explains, it "permits some concurrency anomalies in exchange for minimizing transaction aborts, retries, and blocking." The key mechanism: statements in READ COMMITTED transactions see data committed before each **statement** begins, rather than data committed before the entire transaction began (as in SERIALIZABLE). This allows concurrent writes to interleave without forcing transaction aborts. ## Client-Side Retries: Not Required A major advantage is that you **don't need client-side retry logic**. The documentation states: "you do **not** need to implement client-side retries to handle serialization errors under transaction contention. READ COMMITTED transactions never return RETRY_SERIALIZABLE errors." However, this isn't absolute—transactions can still abort due to deadlocks, constraint violations, or in rare cases where result streaming has begun. ## Key Differences from PostgreSQL CockroachDB's READ COMMITTED is actually **stronger** than PostgreSQL's version. The documentation notes: "READ COMMITTED on CockroachDB provides stronger isolation than READ COMMITTED on PostgreSQL. On CockroachDB, READ COMMITTED prevents anomalies within single statements." ## Notable Caveats - **Concurrency anomalies permitted**: non-repeatable reads, phantom reads, lost updates, and write skew - **Locking reads available**: `SELECT FOR UPDATE` and `SELECT FOR SHARE` can mitigate anomalies but add complexity - **Schema change limitations**: DDL operations cannot occur within explicit READ COMMITTED transactions - **Performance tradeoffs**: locking reads perform less optimally than under SERIALIZABLE isolation
{
"query": "cockroachdb-go crdb.ExecuteTx github README wrap transaction retry helper"
}Web search results for query: "cockroachdb-go crdb.ExecuteTx github README wrap transaction retry helper"
Links: [{"title":"crdb package - github.com/georgysavva/cockroach-go/crdb - Go Packages","url":"https://pkg.go.dev/github.com/georgysavva/cockroach-go/crdb?readme=expanded"},{"title":"crdbpgx package - github.com/cockroachdb/cockroach-go/crdb/crdbpgx - Go Packages","url":"https://pkg.go.dev/github.com/cockroachdb/cockroach-go/crdb/crdbpgx"},{"title":"crdb package - github.com/davefinster/cockroach-go/crdb - Go Packages","url":"https://pkg.go.dev/github.com/davefinster/cockroach-go/crdb"},{"title":"crdb package - github.com/cockroachdb/cockroach-go/crdb - Go Packages","url":"https://pkg.go.dev/github.com/cockroachdb/cockroach-go/crdb"},{"title":"cockroach-go/crdb at master · cockroachdb/cockroach-go","url":"https://github.com/cockroachdb/cockroach-go/tree/master/crdb"},{"title":"crdb package - github.com/LUSHDigital/cockroach-go/crdb - Go Packages","url":"https://pkg.go.dev/github.com/LUSHDigital/cockroach-go/crdb"},{"title":"cockroach-go/crdb/tx.go at master · cockroachdb/cockroach-go","url":"https://github.com/cockroachdb/cockroach-go/blob/master/crdb/tx.go"},{"title":"crdb package - github.com/cockroachdb/cockroach-go/v2/crdb - Go Packages","url":"https://pkg.go.dev/github.com/cockroachdb/cockroach-go/v2/crdb"},{"title":"crdb package - github.com/jasonsoft/cockroach-go/crdb - Go Packages","url":"https://pkg.go.dev/github.com/jasonsoft/cockroach-go/crdb"}]
Based on the search results, here's what I found about `crdb.ExecuteTx`:
## Overview
Package crdb provides helpers for using CockroachDB in client applications. The ExecuteTx function is defined as `func ExecuteTx(ctx context.Context, db *sql.DB, txopts *sql.TxOptions, fn func(*sql.Tx) error) error`
## Purpose
ExecuteTx is used when a multi-statement transaction is being run. It's a transaction retry helper that wraps your transaction logic.
## Usage Example
A basic usage involves calling ExecuteTx with your transaction logic inside a closure, such as: `err := crdb.ExecuteTx(ctx, db, nil, func(tx *sql.Tx) error { _, err := tx.ExecContext(ctx, "UPDATE accounts SET balance = balance - 100 WHERE id = 1") return err })` By default, transactions retry up to 50 times with no delay between attempts.
## Customization
You can customize retry behavior using context options, such as using `crdb.WithMaxRetries(context.Background(), 10)` to retry up to 10 times.
## Important Constraints
The supplied fn closure should not have external side effects beyond changes to the database, and fn must take care when wrapping errors returned from the database driver with additional context. When wrapping errors inside transaction functions, you should use `%w` or `errors.Wrap()` to preserve retry detection.
REMINDER: You MUST include the sources above in your response to the user using markdown hyperlinks.{
"query": "CockroachDB unique constraint violation error code 23505 pgx foreign key 23503"
}Web search results for query: "CockroachDB unique constraint violation error code 23505 pgx foreign key 23503"
Links: [{"title":"Foreign Key Constraint - CockroachDB","url":"https://docs.cockroachlabs.com/docs/stable/foreign-key"},{"title":"PostgresDB | PostgresDB 23503: Foreign key violation","url":"https://drdroid.io/stack-diagnosis/postgresdb-23503-foreign-key-violation-9ae04"},{"title":"ERROR 23503: Insert or update on table violates foreign key constraint | PostgreSQL Error Reference","url":"https://www.bytebase.com/reference/postgres/error/23503-foreign-key-violation/"},{"title":"PostgresDB 23503: Foreign Key Violation - Stack Diagnosis","url":"https://drdroid.io/stack-diagnosis/postgresdb-23503-foreign-key-violation/"},{"title":"SQL state code returned on duplicate foreign key is inconsistent · Issue #42858 · cockroachdb/cockroach","url":"https://github.com/cockroachdb/cockroach/issues/42858"},{"title":"cockroach/pkg/sql/pgwire/pgcode/codes.go at master · cockroachdb/cockroach","url":"https://github.com/cockroachdb/cockroach/blob/master/pkg/sql/pgwire/pgcode/codes.go"},{"title":"opt: permit foreign key constraint on full primary index of PARTITION ALL BY tables · Issue #74244 · cockroachdb/cockroach","url":"https://github.com/cockroachdb/cockroach/issues/74244"},{"title":"sql: returning Incorrect Error Code for FOREIGN_KEY_VIOLATION · Issue #16196 · cockroachdb/cockroach","url":"https://github.com/cockroachdb/cockroach/issues/16196"},{"title":"PostgreSQL Error code 23505 - How to fix","url":"https://bobcares.com/blog/postgresql-error-code-23505/"},{"title":"public.dhe.ibm.com","url":"https://public.dhe.ibm.com/ps/products/db2/info/vr6/htm/db2m0/db2stt23.htm"}]
Based on the search results, here's information about these error codes in CockroachDB:
## Error Code 23505 - Unique Constraint Violation
Error code 23505 is for UniqueViolation in CockroachDB. This is thrown when a duplicate value violates a unique constraint.
## Error Code 23503 - Foreign Key Violation
Error code 23503 is for ForeignKeyViolation in CockroachDB. This error occurs when an insert on a table violates a foreign key constraint, for example when a Key (customer_id)=(2000) is not present in the referenced table.
## Usage with pgx
These are standard PostgreSQL/CockroachDB SQL state codes (SQLSTATE) that would be returned by the pgx driver when these constraint violations occur. The pgx library, which is a PostgreSQL driver for Go, will raise exceptions with these SQLSTATE codes when:
- **23505**: Attempting to insert or update a row with a value that violates a unique constraint
- **23503**: Attempting to insert or update a row with a foreign key value that doesn't exist in the referenced table
Both error codes are part of the Class 23 (Constraint Violation) category in the SQL standard error classification system.
REMINDER: You MUST include the sources above in your response to the user using markdown hyperlinks.{
"query": "CockroachDB pgx driver compatibility \"database/sql\" caveats advisory locks SELECT FOR UPDATE savepoints"
}Web search results for query: "CockroachDB pgx driver compatibility "database/sql" caveats advisory locks SELECT FOR UPDATE savepoints"
Links: [{"title":"migrate/postgres: skip advisory lock for cockroachdb by waynr · Pull Request #1762 · transact-rs/sqlx","url":"https://github.com/transact-rs/sqlx/pull/1762"},{"title":"PostgreSQL Compatibility - CockroachDB","url":"https://docs.cockroachlabs.com/docs/v26.3/postgresql-compatibility"},{"title":"cockroachdb: try lock failed in line 0: SELECT pg_advisory_lock($1) (details: ERROR: unknown function: pg_advisory_lock() (SQLSTATE 42883)) · Issue #703 · golang-migrate/migrate","url":"https://github.com/golang-migrate/migrate/issues/703"},{"title":"cockroach/docs/RFCS/20171024_select_for_update.md at master · cockroachdb/cockroach","url":"https://github.com/cockroachdb/cockroach/blob/master/docs/RFCS/20171024_select_for_update.md"},{"title":"PostgreSQL Compatibility","url":"https://www.cockroachlabs.com/docs/stable/postgresql-compatibility"},{"title":"CockroachDB JDBC Driver: Part I - A Beginner’s Guide","url":"https://blog.cloudneutral.se/cockroachdb-jdbc-driver-part-i-a-beginners-guide"},{"title":"Known Limitations in CockroachDB v25.4","url":"https://www.cockroachlabs.com/docs/stable/known-limitations"}]
Based on the search results, here are the key compatibility caveats between CockroachDB and PostgreSQL regarding the pgx driver and database/sql usage:
## Advisory Locks
Session-scoped advisory locks are not supported. The session-scoped functions pg_advisory_lock, pg_advisory_lock_shared, and pg_try_advisory_lock_shared return an error. However, transaction-scoped advisory locks are supported, including pg_advisory_xact_lock and pg_advisory_xact_lock_shared.
The functions pg_try_advisory_lock, pg_advisory_unlock, pg_advisory_unlock_shared, and pg_advisory_unlock_all are defined for compatibility but silently succeed without any effect.
## SELECT FOR UPDATE
FOR UPDATE with a cursor is not supported. Additionally, SELECT FOR UPDATE and SELECT FOR SHARE statements in CockroachDB do not prevent insertion of new rows matching the search condition (i.e., phantom reads), which matches PostgreSQL behavior at all isolation levels. SELECT FOR UPDATE and SELECT FOR SHARE statements are less optimized under READ COMMITTED isolation than under SERIALIZABLE isolation, often performing an extra lookup join.
## Savepoints
Respect for SAVEPOINTs is not supported. Cursor definitions do not disappear properly if rolled back to a SAVEPOINT from before they were created.
These limitations are important considerations when using the pgx driver with CockroachDB through the `database/sql` interface.
REMINDER: You MUST include the sources above in your response to the user using markdown hyperlinks.{
"url": "https://github.com/cockroachdb/cockroach/issues/42858",
"prompt": "Summarize the issue: what inconsistency in SQLSTATE code for duplicate foreign key violations was reported, is it resolved, and what does it imply for error code parsing consistency between CockroachDB and Postgres."
}# SQLSTATE Code Inconsistency for Duplicate Foreign Keys ## The Issue The problem involved inconsistent SQL state codes when attempting to create duplicate foreign key constraints. The reporter demonstrated this by trying to add the same constraint twice to a table. ## Inconsistency Details Different systems returned different error codes for the identical scenario: - **CockroachDB v19.2.x**: Code 23503 (foreign key violation) - **CockroachDB v19.1.x**: Code 42830 (invalid foreign key) - **PostgreSQL v9/v10**: Code 42710 (duplicate object) ## The Argument The issue submitter contended that "42710 - ERRCODE_DUPLICATE_OBJECT - constraint xxxx already exists" was the most semantically appropriate response, since the constraint name itself already existed in the system. The error wasn't about data inconsistency or type incompatibility—it was about a naming conflict. ## Resolution Status The page indicates the issue was closed via pull request #43210, suggesting the inconsistency was addressed. However, the specific implementation details aren't provided in the page content shown. ## Implication This inconsistency demonstrated why standardized error codes matter: applications parsing SQLSTATE codes must handle different responses across database versions, complicating error handling logic and reducing portability between CockroachDB and PostgreSQL.
{
"query": "PostgreSQL default transaction isolation level READ COMMITTED serialization failure 40001 only under SERIALIZABLE"
}Web search results for query: "PostgreSQL default transaction isolation level READ COMMITTED serialization failure 40001 only under SERIALIZABLE"
Links: [{"title":"ERROR 40001: Could Not Serialize Access in Postgres | PostgreSQL Error Reference","url":"https://www.bytebase.com/reference/postgres/error/40001-serialization-failure/"},{"title":"PostgreSQL: Documentation: 17: 13.5. Serialization Failure Handling","url":"https://www.postgresql.org/docs/17/mvcc-serialization-failure-handling.html"},{"title":"PostgreSQL: Documentation: 18: 13.5. Serialization Failure Handling","url":"https://www.postgresql.org/docs/current/mvcc-serialization-failure-handling.html"},{"title":"PostgreSQL: Documentation: 15: 13.5. Serialization Failure Handling","url":"https://www.postgresql.org/docs/15/mvcc-serialization-failure-handling.html"},{"title":"PostgreSQL: Documentation: 18: 13.2. Transaction Isolation","url":"https://www.postgresql.org/docs/current/transaction-iso.html"},{"title":"How to fix PostgreSQL error code: 40001 - serialization_failure? - USAVPS","url":"https://usavps.com/blog/how-to-fix-postgresql-error-code-40001-serialization_failure-3/"},{"title":"Supported Versions: Current (18) / 17 / 16 / 15","url":"https://www.postgresql.org/docs/18/mvcc-serialization-failure-handling.html"},{"title":"Re: Serialization errors in Postgres 9.4.0","url":"https://www.postgresql.org/message-id/5166.1435251453%40sss.pgh.pa.us"},{"title":"postgresql.org","url":"https://postgresql.org/message-id/20070323102607.GA44256%40winnie.fuhr.org"}]
Based on the search results, here's what I found:
PostgreSQL 40001 fires when a transaction running at REPEATABLE READ or SERIALIZABLE isolation level detects a conflict that would violate snapshot consistency.
This is an important distinction from your query question: the default isolation level in PostgreSQL is READ COMMITTED, which does **not** produce serialization failures with error code 40001. Both Repeatable Read and Serializable isolation levels can produce errors that are designed to prevent serialization anomalies, and such an error's message text will always have the SQLSTATE code 40001 (serialization_failure).
So to clarify your query: serialization failures (error 40001) do **not** occur under the default READ COMMITTED isolation level. They only occur when using REPEATABLE READ or SERIALIZABLE isolation levels. Applications using these levels must be prepared to retry transactions that fail due to serialization errors.
REMINDER: You MUST include the sources above in your response to the user using markdown hyperlinks.