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memorize.ai (lvl 286)

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What is materialized view

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SQL

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7 years ago

Date created

Mar 1, 2020

Cards (8)

Section 1

(8 cards)

What is materialized view

Front

These are disk based views. These are updated at a specified interval. You can create index on them.

Back

Composite Primary Key

Front

Set of columns to uniquely identify "all" the records in a table.

Back

Composite Key

Front

Set of columns to uniquely identify "a" record in a table

Back

ACID

Front

Atomicity: All the queries in transactions should behave like one. One fails, all fail. All pass, all pass. Consistency: DB will go from one consistent state to another if txn passes otherwise stays the same. Isolation: Every txn should work as if there is only one txn in the system. Durability: Once txn completes all the rows should be available for other txns.

Back

Database Lock

Front

Tells if data is being used by another txn/query.

Back

Shared vs Exclusive Lock

Front

With shared lock, other txns can read the data but not with exclusive lock.

Back

Unique Key

Front

Similar to Primary Key but allows null value. There can be many UK in a table It creates non clustered index and PK creates clustered.

Back

What are wild card used for pattern matching

Front

Like is used. 1. Do not overuse it as wild cards are slowest. 2. try to move wild cards at the end of the query.

Back