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| <h1 id="concurrent-writes"><a class="header" href="#concurrent-writes">Concurrent Writes</a></h1> |
| <p>When multiple writers commit to the same table, iceberg-go uses optimistic |
| concurrency control: every commit is validated against the table state it was |
| built on. If another writer committed first, the commit is rejected rather than |
| silently clobbering their snapshot.</p> |
| <h2 id="conflict-detection"><a class="header" href="#conflict-detection">Conflict detection</a></h2> |
| <p>Each producer (<code>Append</code>, <code>Overwrite</code>, <code>Delete</code>, <code>RowDelta</code>, <code>RewriteDataFiles</code>) |
| runs a set of validators before the commit lands. They check that the files the |
| operation assumed (added, deleted, or filtered) still match the current table |
| state. A failed validation surfaces as one of:</p> |
| <ul> |
| <li><code>table.ErrCommitFailed</code> — the base snapshot moved on; the commit can be |
| retried after refreshing (see below).</li> |
| <li><code>table.ErrCommitDiverged</code> — terminal. The base snapshot is no longer on the |
| branch at all, so a retry cannot reconcile the change.</li> |
| </ul> |
| <pre><code class="language-go">import ( |
| "context" |
| "errors" |
| |
| "github.com/apache/iceberg-go/table" |
| ) |
| |
| _, err := txn.Commit(context.Background()) |
| switch { |
| case errors.Is(err, table.ErrCommitDiverged): |
| // unrecoverable: rebuild the operation from the latest table |
| case errors.Is(err, table.ErrCommitFailed): |
| // retriable: refresh and try again (the retry loop does this for you) |
| } |
| </code></pre> |
| <h2 id="isolation-levels"><a class="header" href="#isolation-levels">Isolation levels</a></h2> |
| <p>Delete and update operations are validated under an isolation level, set per |
| operation through table properties:</p> |
| <div class="table-wrapper"><table><thead><tr><th style="text-align: left">Property</th><th style="text-align: left">Default</th><th style="text-align: left">Values</th></tr></thead><tbody> |
| <tr><td style="text-align: left"><code>write.delete.isolation-level</code></td><td style="text-align: left"><code>serializable</code></td><td style="text-align: left"><code>serializable</code>, <code>snapshot</code></td></tr> |
| <tr><td style="text-align: left"><code>write.update.isolation-level</code></td><td style="text-align: left"><code>serializable</code></td><td style="text-align: left"><code>serializable</code>, <code>snapshot</code></td></tr> |
| </tbody></table> |
| </div> |
| <p><code>serializable</code> rejects the commit if <em>any</em> concurrent snapshot added data |
| matching the operation's filter. <code>snapshot</code> is more permissive — it only |
| rejects when concurrent deletes touch the same files.</p> |
| <h2 id="automatic-retry"><a class="header" href="#automatic-retry">Automatic retry</a></h2> |
| <p>iceberg-go can refresh the table and replay the operation against the latest |
| snapshot between attempts. On each retry the table metadata is reloaded, the |
| producer's validators re-run against the fresh snapshot, and the commit is |
| re-submitted only if it is still valid.</p> |
| <p>Retry is <strong>off by default</strong> (<code>commit.retry.num-retries</code> is <code>0</code>). Opt in by |
| setting the retry properties — see <a href="./configuration.html#manifest-and-commit">Manifest and commit</a> |
| in the configuration reference for the full list:</p> |
| <pre><code class="language-go">// Opt in to retries (e.g. 4 attempts after the first) for a contended table. |
| _, err := cat.CreateTable(ctx, ident, schema, |
| catalog.WithProperties(iceberg.Properties{ |
| "commit.retry.num-retries": "4", |
| }), |
| ) |
| </code></pre> |
| <blockquote> |
| <p><strong>Catalog support:</strong> retry currently engages on the REST catalog, which wraps |
| commit conflicts as <code>ErrCommitFailed</code>. The Glue, SQL, and Hive catalogs do |
| not yet wrap their conflict errors, so the retry loop will not fire on them.</p> |
| </blockquote> |
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