If you hit that specific problem, it*could*make more sense to physically cluster/sort your table data on a random value – like aUNIQUEIDENTIFIERcolumn. In that case you can still use the Primary Key constraint on the original ever-increasing key column, but enforce it with a Unique Non-C...
"meaning" or purpose (the surrogate key) also adds to the table storage space. Since the NetworkID can change, it's not a good choice for the primary key. Using a surrogate key would allow you to change the network ID and not update the UserMenu table, so I think that is a good ...
Evil, I know what a clustered index is, my question was about Unique index(clustered) vs Primary key. Paul, The 1 NULL value I had not thought about. Pragmatically however, I cannot imagine that being a consideration on deciding what to choose, unique index or primkey. I admit I myself...
Type of KeyIt uses the primary key as a clustered index.It can work with unique constraints that act as a composite key. Contains in TableA table can only one clustered index.A table can contain one or more than a non-clustered index. ...
GUIDs as PRIMARY KEYs and/or the clustering key The Clustered Index Debate Continues... Ever-increasing clustering key - the Clustered Index Debate...again! Disk space is cheap - that's not the point! Thanks marc_s for the clear explanation. But technically speaking, what does non ...
If you do not define aPRIMARY KEYfor a table,InnoDBuses the firstUNIQUEindex with all key columns defined asNOT NULLas the clustered index. If a table has noPRIMARY KEYor suitableUNIQUEindex,InnoDBgenerates a hidden clustered index namedGEN_CLUST_INDEXon a synthetic column that contains row ID...
Key Differences are listed below, Cluster Index Non-Cluster Index It can have only one Cluster Index per table. It can have more than one Non-Cluster Index per table. It cannot consume extra disk storage as it only sorts data rows in the table. It can consume more disk storage space as...
Tables With A Single Index On An Ascending Key If your table has a single index on a primary key, you probably want a cluster index. This is the default behaviour of SQL Server. But WHY is this so? Consider the case of INSERT statements in these two tables: ...
Another concept that should be mentioned is a primary key. A primary key is aunique keyfor each record in a table that allows SQL Server to go directly to that one row. Not all tables have a primary key, but it is always better to have one when possible. ...
Clustered vs Nonclustered Indexes in SQL The difference between Clustered and Nonclustered indexin a relational database is one of the most popular SQL interview questions almost as popular as theprimary key vs unique key, thedifference between truncate and delete, andcorrelated vs noncorrelated subq...