What is the difference between local index and Global index?
Global Index: A global index is a one-to-many relationship, allowing one index partition to map to many table partitions. Local Index: A local index is a one-to-one mapping between a index partition and a table partition.
What is a local index?
Local indexes are indexes that are partitioned using the same partition key and same range boundaries as the partitioned table. Each partition of a local index will only contain keys and ROWIDs from its corresponding table partition. Local indexes can be b-tree or bitmap indexes.
What are indexes in Sybase?
In a database, an index lets you speed queries by setting pointers that let you retrieve table data without scanning the entire table. An index can be unique or non-unique. Sybase ASE creates indexes as B-Trees, which are a series of pointers mapping index pages to their underlying data pages.
What is a global index?
A global index, by very definition, is a single index on the parent table that maps to many underlying table partitions. In very crude terms, the global index accumulates data in one place so that data spanning across multiple partitions are accessed in one go as opposed to individually querying each partition.
What is a global partitioned index?
In a global partitioned index, the keys in a particular index partition may refer to rows stored in multiple underlying table partitions or subpartitions. A global index can be range or hash partitioned, though it can be defined on any type of partitioned table. Index partitions can be merged or split as necessary.
What is local secondary index?
A local secondary index maintains an alternate sort key for a given partition key value. A local secondary index also contains a copy of some or all of the attributes from its base table. The data in a local secondary index is organized by the same partition key as the base table, but with a different sort key.
What is a local index in Oracle?
A local index is equipartitioned with the underlying table. Oracle Database partitions the index on the same columns as the underlying table, creates the same number of partitions or subpartitions, and gives them the same partition boundaries as corresponding partitions of the underlying table.
How do I create an index in Sybase?
To create a nonunique clustered index on a table that contains duplicate rows, specify allow_dup_row or ignore_dup_row. See “Duplicate rows”. When you create a unique local index on range-, list-, and hash-partitioned tables, the index key list is a superset of the partition-key list.
How do I drop an index in Sybase?
To drop such indexes, drop the constraints through alter table or drop the table. See create table for more information about unique constraint indexes. You cannot drop indexes that are currently used by any open cursor. For information about which cursors are open and what indexes they use, use sp_cursorinfo.
What happens to index when table is partitioned?
When partitioning a unique nonclustered index, the index key must contain the partitioning column. When partitioning a nonunique, nonclustered index, SQL Server adds the partitioning column by default as a nonkey (included) column of the index to make sure the index is aligned with the base table.
What’s the difference between local index and global index?
A local partitioned index creates one-to-one relationship between the table partitions. The key value for the table partition and the index partition must be identical. When you create a local index on a partitioned table, it automatically creates index partitions as many as in the table partitions.
What’s the difference between local and global indexes in DynamoDB?
Local secondary index — an index that has the same hash key as the table, but a different range key. A local secondary index is “local” in the sense that every partition of a local secondary index is scoped to a table partition that has the same hash key.
Is the primary key a global or local index?
Yes, the primary key is a global index. If some table data was moved to another partition, any indexes pointing to that data would be updated accordingly. (Is that what you meant with your last question?)
Is there a dependency on the global index?
There is no dependency in Global index partitioned key and Table partition key. The partition maximum bound is defined by the keyword MAXVALUE. You can add partitions to the global partition index by splitting the MAXVALUE partition. Using “alter index drop partition” you can drop a empty global index partition.