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is primary key always indexed. This tutorial covers the Cassandra primary and secondary indexes for query performance Cassandra Primary key is the row key and is always index. Also, empty strings can be indexed for faster search, unlike NULLs. The primary key attribute which Pony adds automatically always will have the name id and  For example, the node table vid field description might contain Always holds the primary key An array of one or more key column specifiers (see below) that a unique key named vid on field vid , and two indexes, one named nid on  Starting at the very beginning… a primary key is used to enforce entity index) and, it s always been a potential source of fragmentation. In InnoDB, every SECONDARY INDEX contains the PRIMARY KEY column(s) together with the column(s) of the secondary index, automatically. That is because  When you create a Django model, by default it adds a primary key. This uniqueness is implemented via an index in PostgreSQL. There are some database designers that insist that primary keys always be surrogate keys,  Please clear my doubt about this, In SQL Server (2000 and above) is primary key automatically cluster indexed or do we have choice to have  Always dense, usually with duplicates Consists of key-pointer pairs ( key . B-tree search key is primary key for data file, leaf pointers form a dense index on  Because the SQL Server query processor uses the primary key index for lookups . The properties of uniqueness and immutability are not always present in the  So the above told me I can create a clustered index on columns other than primary key. I think it also conveys that a primary key should either be a nonclustered  Do you need to explicitly create an index, or is it implicit when defining the primary key Is the answer the same for MyISAM and InnoDB A unique primary index (UPI) will always spread the rows of the table evenly The primary index is the key to determine where the ROW of the table will reside  Record sequential files are nearly always referred to simply as sequential files because . An indexed file is a file in which each record includes a primary key. Secondary indexes are on the non-primary key, which gives ability to model one The changes which eventually are made to the secondary index are always 

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