private void dropTableIndexes(TableInfo tableInfo) throws IOException {
String tableName = tableInfo.getTableName();
// We need to open the table so that we can drop all related objects,
// such as indexes on the table, etc.
TableSchema schema = tableInfo.getTupleFile().getSchema();
// Check whether this table is referenced by any other tables via
// foreign keys. Need to check the primary key and candidate keys.
KeyColumnRefs pk = schema.getPrimaryKey();
if (pk != null && !pk.getReferencingIndexes().isEmpty()) {
throw new IOException(
"Drop table failed due to the table" + " having foreign key dependencies: " + tableName);
}
List<KeyColumnRefs> candKeyList = schema.getCandidateKeys();
for (KeyColumnRefs candKey : candKeyList) {
if (!candKey.getReferencingIndexes().isEmpty()) {
throw new IOException(
"Drop table failed due to the table"
+ " having foreign key dependencies: "
+ tableName);
}
}
// If we got here, the table being dropped is not a referenced table.
// Start cleaning up various schema objects for the table.
List<KeyColumnRefs> parentCandKeyList;
TableInfo parentTableInfo;
// Now drop the foreign key constraint fields that this table
// may have on other parent tables. Scan through this table's
// Foreign key indexes to see which tables need maintenance
List<ForeignKeyColumnRefs> forKeyList = schema.getForeignKeys();
for (ForeignKeyColumnRefs forKey : forKeyList) {
// Open the parent table, and iterate through all of its primary
// and candidate keys, dropping any foreign key constraints that
// refer to the child table with tableName
String parentTableName = forKey.getRefTable();
try {
parentTableInfo = openTable(parentTableName);
} catch (Exception e) {
throw new IOException(
"The referenced table, "
+ parentTableName
+ ", which is referenced by "
+ tableName
+ ", does not exist.");
}
TableSchema parentSchema = parentTableInfo.getTupleFile().getSchema();
KeyColumnRefs parentPK = parentSchema.getPrimaryKey();
if (parentPK != null) {
parentPK.dropRefToTable(tableName);
}
parentCandKeyList = parentSchema.getCandidateKeys();
for (KeyColumnRefs parentCandKey : parentCandKeyList) {
parentCandKey.dropRefToTable(tableName);
}
// Persist the changes we made to the schema
saveTableInfo(parentTableInfo);
}
// Then drop the indexes since we've checked the constraints
IndexManager indexManager = storageManager.getIndexManager();
for (String indexName : schema.getIndexes().keySet())
indexManager.dropIndex(tableInfo, indexName);
}
