guykhazma commented on code in PR #12228:
URL: https://github.com/apache/iceberg/pull/12228#discussion_r2040032952
##########
core/src/main/java/org/apache/iceberg/BaseMetastoreCatalog.java:
##########
@@ -71,23 +70,35 @@ public Table loadTable(TableIdentifier identifier) {
}
@Override
- public Table registerTable(TableIdentifier identifier, String
metadataFileLocation) {
+ public Table registerTable(
+ TableIdentifier identifier, String metadataFileLocation, boolean
overwrite) {
Preconditions.checkArgument(
identifier != null && isValidIdentifier(identifier), "Invalid
identifier: %s", identifier);
Preconditions.checkArgument(
metadataFileLocation != null && !metadataFileLocation.isEmpty(),
"Cannot register an empty metadata file location as a table");
- // Throw an exception if this table already exists in the catalog.
- if (tableExists(identifier)) {
+ // If the table already exists and overwriting is disabled, throw an
exception.
+ if (tableExists(identifier) && !overwrite) {
throw new AlreadyExistsException("Table already exists: %s", identifier);
}
TableOperations ops = newTableOps(identifier);
- InputFile metadataFile = ops.io().newInputFile(metadataFileLocation);
- TableMetadata metadata = TableMetadataParser.read(ops.io(), metadataFile);
- ops.commit(null, metadata);
-
+ TableMetadata newMetadata =
+ TableMetadataParser.read(ops.io(),
ops.io().newInputFile(metadataFileLocation));
+
+ TableMetadata existing = ops.current();
+ if (existing != null && overwrite) {
+ if (existing.metadataFileLocation().equals(metadataFileLocation)) {
+ LOG.info(
+ "The requested metadata matches the existing metadata. No changes
will be committed.");
+ return new BaseTable(ops, fullTableName(name(), identifier),
metricsReporter());
+ }
+ dropTable(identifier, false /* Keep all data and metadata files */);
Review Comment:
@dramaticlly Could you elaborate on why you see this as a state overwrite?
I can imagine a scenario where some state or partial state is transferred
from another table (with a different UUID), which might be interpreted as a
state change. However, I’m not sure the register API is the appropriate
mechanism for that.
From my understanding, the purpose of the register API is to create a named
reference to a metadata JSON. It doesn’t inherently imply any change to the
actual state of a table. Even if you register it against an existing table and
the resulting metadata reflects a different state, it doesn’t mean that the
underlying storage state has changed.
For instance, it's possible to register the same table multiple times under
different names using distinct metadata files—effectively simulating branching
using different entries in the catalog.
##########
core/src/main/java/org/apache/iceberg/BaseMetastoreCatalog.java:
##########
@@ -71,23 +70,35 @@ public Table loadTable(TableIdentifier identifier) {
}
@Override
- public Table registerTable(TableIdentifier identifier, String
metadataFileLocation) {
+ public Table registerTable(
+ TableIdentifier identifier, String metadataFileLocation, boolean
overwrite) {
Preconditions.checkArgument(
identifier != null && isValidIdentifier(identifier), "Invalid
identifier: %s", identifier);
Preconditions.checkArgument(
metadataFileLocation != null && !metadataFileLocation.isEmpty(),
"Cannot register an empty metadata file location as a table");
- // Throw an exception if this table already exists in the catalog.
- if (tableExists(identifier)) {
+ // If the table already exists and overwriting is disabled, throw an
exception.
+ if (tableExists(identifier) && !overwrite) {
throw new AlreadyExistsException("Table already exists: %s", identifier);
}
TableOperations ops = newTableOps(identifier);
- InputFile metadataFile = ops.io().newInputFile(metadataFileLocation);
- TableMetadata metadata = TableMetadataParser.read(ops.io(), metadataFile);
- ops.commit(null, metadata);
-
+ TableMetadata newMetadata =
+ TableMetadataParser.read(ops.io(),
ops.io().newInputFile(metadataFileLocation));
+
+ TableMetadata existing = ops.current();
+ if (existing != null && overwrite) {
+ if (existing.metadataFileLocation().equals(metadataFileLocation)) {
+ LOG.info(
+ "The requested metadata matches the existing metadata. No changes
will be committed.");
+ return new BaseTable(ops, fullTableName(name(), identifier),
metricsReporter());
+ }
+ dropTable(identifier, false /* Keep all data and metadata files */);
Review Comment:
thank you @dramaticlly, Could you elaborate on why you see this as a state
overwrite?
I can imagine a scenario where some state or partial state is transferred
from another table (with a different UUID), which might be interpreted as a
state change. However, I’m not sure the register API is the appropriate
mechanism for that.
From my understanding, the purpose of the register API is to create a named
reference to a metadata JSON. It doesn’t inherently imply any change to the
actual state of a table. Even if you register it against an existing table and
the resulting metadata reflects a different state, it doesn’t mean that the
underlying storage state has changed.
For instance, it's possible to register the same table multiple times under
different names using distinct metadata files—effectively simulating branching
using different entries in the catalog.
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