2
votes
3answers
67 views

Listing indexes and constraints

I am looking at a SQL Server database for an application I have inherited. I have not looked into SQL Server for approximately 10 years, so please bear with me. The database table I am looking at has ...
2
votes
0answers
48 views

Postgres 9.3 - deletes terribly slow for 10 minutes after dropping indexes/constraints

If I run a script which drops indexes (17 of them, CONCURRENTLY makes no difference except that without it I get the occasional deadlock), then constraints (20 constraints on 18 tables) and then run a ...
4
votes
2answers
321 views

Custom unique column constraint, only enforced if one column has a specific value

Is it possible to have a custom unique column constraint as follows? Suppose I have two cols, subset and type, both strings (though the data types probably doesn't matter). If type is "true", then ...
1
vote
1answer
351 views

SQL Azure: Drop Constraint and Index

This may be a stupid question, but I'm not a DBA and just wanna make sure of what I'm doing before I make a mistake. Here is my question: When dropping Constraints, are their indexes dropped as well? ...
0
votes
1answer
127 views

Microsoft Access - performance difference between index and constraint?

I've looked around a bit but haven't come across anything talking specifically about MS Access. So: what, if any, is the performance difference between a field with a constraint and a field with an ...
0
votes
1answer
61 views

Is it any potential problem with having 2 constraints suppored by one index in Oracle?

I have the following table : CREATE TABLE action (action_id INT NOT NULL, action_type_id INT NOT NULL, action_date DATE NOT NULL); CREATE INDEX IDX_ACTION_ACT_TYPE_ACT ON action(action_id, ...
1
vote
1answer
740 views

MySQL: Unique constraint on large column

I am trying to create an InnoDB table that contains a VARCHAR column that can hold up to 3071 characters. I would like to enforce a UNIQUE constraint on the data of this column. MySQL appears to ...
1
vote
2answers
355 views

Would existing constraints and indexes applied to an old table, apply to a new table renamed like the old one after it's dropped?

everything is in the question. I have a table named tableA on which we have indexes and foreign keys and constraints. I have to modify content in a column called column1. This being a production ...
2
votes
3answers
308 views

SQL Server : explicitly create an index on a primary key and unique fields

UPDATED: I'll make the question clearer as the first answer isn't quite what I was looking for. How can I execute this create table statement and ensure that the two automatically created indexes ...
5
votes
2answers
140 views

Unique Contraint/Index Based On Values

I have a table that has the following column definitions: ID (INT, PK) Name (VarChar) Active (Bit) Bunch_of (Other_columns) Question: I want to have a Constraint on Name/Active such that we can ...
28
votes
5answers
8k views

When should I use a unique constraint instead of a unique index?

When I want a column to have distinct values, I can either use a constraint create table t1( id int primary key, code varchar(10) unique NULL ); go or I can use a unique index create table t2( id ...