What causes "Materialized view already exists" in prestodb/presto?

Use CREATE MATERIALIZED VIEW IF NOT EXISTS or pass ignoreExisting = true

prestodb/presto · error · MaterializedViewAlreadyExistsException

Materialized view already exists

Error message

Materialized view already exists

What it means

Converted from TableAlreadyExistsException at the end of createMaterializedView: the metastore createTable call (with ignoreExisting honored) found that an object already exists under the materialized view's name, so MaterializedViewAlreadyExistsException is raised. The name is taken by some existing table or materialized view.

Source

Thrown at presto-hive/src/main/java/com/facebook/presto/hive/HiveMetadata.java:2677

                .setViewExpandedText(Optional.of("/* Presto Materialized View */"))
                .build();

        MetastoreContext metastoreContext = getMetastoreContext(session);
        validateMaterializedViewPartitionColumns(metastore, metastoreContext, viewTable, viewDefinition);

        try {
            PrincipalPrivileges principalPrivileges = buildInitialPrivilegeSet(viewTable.getOwner());
            metastore.createTable(
                    session,
                    viewTable,
                    principalPrivileges,
                    Optional.empty(),
                    ignoreExisting,
                    new PartitionStatistics(createEmptyStatistics(), ImmutableMap.of()),
                    emptyList());
        }
        catch (TableAlreadyExistsException e) {
            throw new MaterializedViewAlreadyExistsException(e.getTableName());
        }
    }

    @Override
    public void dropMaterializedView(ConnectorSession session, SchemaTableName viewName)
    {
        Optional<MaterializedViewDefinition> view = getMaterializedView(session, viewName);
        if (!view.isPresent()) {
            throw new MaterializedViewNotFoundException(viewName);
        }

        try {
            metastore.dropTable(
                    new HdfsContext(session, viewName.getSchemaName(), viewName.getTableName()),
                    viewName.getSchemaName(),
                    viewName.getTableName());
        }
        catch (TableNotFoundException e) {

View on GitHub (pinned to 55bb57d202)

Solutions

Use CREATE MATERIALIZED VIEW IF NOT EXISTS or pass ignoreExisting = true
Drop the existing object first (DROP MATERIALIZED VIEW / DROP TABLE as appropriate)
Coordinate deployments so only one pipeline creates the view
Catch MaterializedViewAlreadyExistsException and treat as no-op when definitions match

Example fix

-- before
CREATE MATERIALIZED VIEW mv_daily AS SELECT ...;
-- after
CREATE MATERIALIZED VIEW IF NOT EXISTS mv_daily AS SELECT ...;

Defensive patterns

Strategy: try-catch

Try / catch

try {
    createMaterializedView(session, metadata, definition, ignoreExisting);
} catch (MaterializedViewAlreadyExistsException e) {
    if (!ignoreExisting) {
        run("DROP MATERIALIZED VIEW IF EXISTS " + e.getTableName());
        createMaterializedView(session, metadata, definition, ignoreExisting);
    }
}

Prevention

Use IF NOT EXISTS for idempotent deployments
Pass ignoreExisting=true in re-runnable jobs
Avoid two pipelines creating the same MV concurrently
Clean up leftovers from failed runs before retrying

When it happens

Trigger: CREATE MATERIALIZED VIEW where the target name already exists in the metastore; a race where another session creates the same name after the existence check; re-running the same DDL without IF NOT EXISTS/ignoreExisting.

Common situations: CI/CD re-deploying the same materialized view definition; two pipelines materializing the same aggregate concurrently; leftover object from a previous failed drop.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/0fe03c752f319e08. Report an issue: GitHub.