Getting SQL Server Cross database Dependencies - sql

Question

SQL Server Version - 2008 R2
I am working on evaluating a DMS solution, with an objective of taking over maintenance. The original solution has one central database, that has data pertaining to the manufacturer. It also has one database for each dealer, which means there are a lot of cross database dependencies.
The problems:
No DB documentation
No code comments
Lots of heaps
No standard object naming conventions
The central DB has 460+ tables and 900+ SProcs, in addition to other
objects
Each dealer DB has 370+ tables and 2350+ SProcs, in addition to other
objects
As a first step, I am recommending a complete clean-up of the DB, for which it is critical to understand object dependencies, including cross database dependencies. I tried using Red Gate's solution, but the output is way too voluminous. All I want is a list of objects in the databases that do not have any dependencies - they neither depend on other objects, nor are there any objects that depend on them.
Here is the script I have used to get a list of dependencies:
SELECT
DB_NAME() referencing_database_name,
OBJECT_NAME (referencing_id) referencing_entity_name,
ISNULL(referenced_schema_name,'dbo') referenced_schema_name,
referenced_entity_name,
ao.type_desc referenced_entity_type,
ISNULL(referenced_database_name,DB_NAME()) referenced_database_name
FROM sys.sql_expression_dependencies sed
JOIN sys.all_objects ao
ON sed.referenced_entity_name = ao.name
I will be creating a table - Dependencies - into which I will be inserting this result set from each DB. As a next step, I will also be creating another table - AllObjects- which will contain a list of all objects in the Databases. Here is the script to do this:
SELECT
DB_NAME() DBName,
name,
type_desc
FROM sys.all_objects
WHERE type_desc IN
(
'VIEW',
'SQL_TABLE_VALUED_FUNCTION',
'SQL_STORED_PROCEDURE',
'SQL_INLINE_TABLE_VALUED_FUNCTION',
'USER_TABLE',
'SQL_SCALAR_FUNCTION'
)
Now, a list of name from this table, that do not appear in the referenced_entity_name column in the dependencies table should give a list of objects that I am looking for.
SELECT
AO.DBName,
AO.name,
AO.type_desc
FROM AllObjects AO
LEFT OUTER JOIN Dependencies D ON
D.referenced_database_name = AO.DBName AND
D.referenced_entity_name = AO.name AND
D.referenced_entity_type = AO.type_desc
WHERE
D.referenced_database_name IS NULL AND
D.referenced_entity_name IS NULL AND
D.referenced_entity_type IS NULL
Now the questions:
Some object dependencies seem to be missing in the output. What am I
missing?
How do I validate that my findings are correct?
I mean is there a different way to do this, so I can compare the
results and double check?
Thanks in advance,
Raj

Answer 1

You can compare your results to the ones that the following script finds.
Here is the full article
CREATE PROCEDURE [dbo].[get_crossdatabase_dependencies] AS
SET NOCOUNT ON;
CREATE TABLE #databases(
database_id int,
database_name sysname
);
INSERT INTO #databases(database_id, database_name)
SELECT database_id, [name]
FROM sys.databases
WHERE 1 = 1
AND [state] <> 6 /* ignore offline DBs */
AND database_id > 4; /* ignore system DBs */
DECLARE
#database_id int,
#database_name sysname,
#sql varchar(max);
CREATE TABLE #dependencies(
referencing_database varchar(max),
referencing_schema varchar(max),
referencing_object_name varchar(max),
referenced_server varchar(max),
referenced_database varchar(max),
referenced_schema varchar(max),
referenced_object_name varchar(max)
);
WHILE (SELECT COUNT(*) FROM #databases) > 0 BEGIN
SELECT TOP 1 #database_id = database_id,
#database_name = database_name
FROM #databases;
SET #sql = 'INSERT INTO #dependencies select
DB_NAME(' + convert(varchar,#database_id) + '),
OBJECT_SCHEMA_NAME(referencing_id,'
+ convert(varchar,#database_id) +'),
OBJECT_NAME(referencing_id,' + convert(varchar,#database_id) + '),
referenced_server_name,
ISNULL(referenced_database_name, db_name('
+ convert(varchar,#database_id) + ')),
referenced_schema_name,
referenced_entity_name
FROM ' + quotename(#database_name) + '.sys.sql_expression_dependencies';
EXEC(#sql);
DELETE FROM #databases WHERE database_id = #database_id;
END;
SET NOCOUNT OFF;
SELECT * FROM #dependencies;

Answer 2

Oh, MS made a good effort at detecting cross-database dependencies with sys.sql_expression_dependencies, but I've seen it miss things before. In your case, I'd find an example of a missing dependency, and start backtracking: have you dropped it from your query some how? If so, fix your query. Does sys.sql_expression_dependencies omit a certain class of dependencies? Under what conditions? Is dynamic SQL to blame? etc.
You should also run sp_refreshsqlmodule for each object in sys.sql_modules, and then rerun your code. It forces SQL Server to refresh the dependency info (to the best of its ability).
Now, for validation, set up a trace, and listen for event 114, "Audit Schema Object Access Event", plus the starting and completed events for stored procedure and/or RPC calls. Include columns DatabaseName, ParentName, ObjectName, ServerName, SPID and RequestID (for MARS-enabled connections). Maybe some others too. "Audit Schema Object Access Event" happens anytime an object is accessed, so exercise the app while this trace is running, then collate the data using SPID + RequestId and compare it to your results using sys.sql_expression_dependencies. If anything is in the trace data that doesn't appear in your dependencies data, then you've missed something.

Answer 3

If you have to deal with linked servers, I adapted #MilicaMedic's answer to work for cross-server dependencies. I also output column names where available in a dependency.
You can use it like this:
create table #dependencies (
referencing_server nvarchar(128),
referencing_database nvarchar(128),
referencing_schema nvarchar(128),
referencing_object_name nvarchar(128),
referencing_column nvarchar(128),
referenced_server nvarchar(128),
referenced_database nvarchar(128),
referenced_schema nvarchar(128),
referenced_object_name nvarchar(128),
referenced_column nvarchar(128)
);
insert #dependencies
exec crossServerDependencies
'ThisServerName, LinkedServerName, LinkedServerName2, etc'
From there you join it to your AllObjects table as you described in your answer.
My code requires two external functions: "splitString", and "AddBracketsWhenNecessary". You can simplify the former and completely eliminate the latter, as you desire. But I use them for other things so they make it into my implementation. The code for both is at the bottom.
Here is the main procedure:
create procedure crossServerDependencies
#server_names_csv nvarchar(500) = null -- csv list of server names you want to pull dependencies for
as
-- Create output table
if object_id('tempdb..#dependencies') is not null
drop table #dependencies;
create table #dependencies (
referencing_server nvarchar(128),
referencing_database nvarchar(128),
referencing_schema nvarchar(128),
referencing_object_name nvarchar(128),
referencing_column nvarchar(128),
referenced_server nvarchar(128),
referenced_database nvarchar(128),
referenced_schema nvarchar(128),
referenced_object_name nvarchar(128),
referenced_column nvarchar(128)
);
-- Split server csv into table
set #server_names_csv = isnull(#server_names_csv, ##servername);
declare #server_names table (
server_row int,
server_name nvarchar(128),
actuallyExists bit
);
insert #server_names
select server_row = id,
server_name,
actuallyExists = case when sv.name is not null then 1 else 0 end
from dbo.splitString(#server_names_csv, ',') sp
cross apply (select server_name = dbo.AddBracketsWhenNecessary(val)) ap
left join sys.servers sv on sp.val = dbo.AddBracketsWhenNecessary(sv.name);
-- Loop servers
declare
#server_row int = 0,
#server_name nvarchar(50),
#server_exists bit = 0,
#server_is_local bit = 0,
#server_had_some_inserts bit = 0;
while #server_row <= (select max(server_row) from #server_names)
begin
-- Server loop initializations
set #server_row += 1;
set #server_had_some_inserts = 0;
select #server_name = server_name,
#server_exists = actuallyExists
from #server_names
where server_row = #server_row;
set #server_is_local =
case when #server_name = dbo.AddBracketsWhenNecessary(##servername) then 1 else 0 end;
-- Handle non-existent server (and prevent sql injection)
if #server_exists = 0
begin
print
'"' + #server_name + '" does not exist. ' +
'Please check your spelling and/or access to view the linked server ' +
'(running under ' + user_name() + ').';
continue;
end
-- Get database list
if object_id('tempdb..#databases') is not null
drop table #databases;
create table #databases (
rownum int identity(1,1),
database_id int,
database_name nvarchar(128)
);
declare #sql nvarchar(max) = '
select database_id, [name]
from master.sys.databases
where state <> 6 -- ignore offline dbs
and database_id > 4 -- ignore system dbs
and has_dbaccess([name]) = 1
and [name] not in (''ReportServer'', ''ReportServerTempDB'')
';
if #server_is_local = 0
begin
set #sql = replace(#sql, '''', '''''');
set #sql = 'select * from openquery( #server_name, ''' + #sql + ''')';
end
set #sql = 'insert #databases (database_id, database_name)' + #sql;
set #sql = replace(#sql, '#server_name', #server_name);
exec (#sql);
delete #databases
where database_name = 'ReportServer';
-- Loop databases
declare #rowNum int = 0;
while #rowNum <= (select max(rownum) from #databases)
begin
-- Database loop initializations
set #rowNum += 1;
declare
#database_id nvarchar(max),
#database_name nvarchar(max);
select #database_id = database_id,
#database_name = dbo.AddBracketsWhenNecessary(database_name)
from #databases
where rownum = #rowNum;
-- Get object dependency info
set #sql = '
with
getTableColumnIds as (
select table_id = o.object_id,
table_name = o.name,
column_id = c.column_id,
column_name = c.name
from #database_name.sys.objects o
join #database_name.sys.all_columns c on o.object_id = c.object_id
)
#insertStatement
select ''#server_name'',
db_name(#database_id),
object_schema_name(referencing_id, #database_id),
object_name(referencing_id, #database_id),
referencing_column = ringTCs.column_name,
isnull(referenced_server_name, ''#server_name''),
isnull(referenced_database_name, db_name(#database_id)),
isnull(referenced_schema_name, ''dbo''),
referenced_entity_name,
referenced_column = redTCs.column_name
from #database_name.sys.sql_expression_dependencies d
left join getTableColumnIds ringTCs
on d.referencing_id = ringTCs.table_id
and d.referencing_minor_id = ringTCs.column_id
left join getTableColumnIds redTCs
on d.referenced_id = redTCs.table_id
and d.referenced_minor_id = redTCs.column_id
';
set #sql = replace(#sql, '#database_id', #database_id);
set #sql = replace(#sql, '#database_name', #database_name);
if #server_is_local = 0
begin
set #sql = replace(#sql, '''', '''''');
set #sql = replace(#sql, '#insertStatement', '');
set #sql = 'select * from openquery(#server_name, ''' + #sql + ''')';
end
set #sql = replace(#sql, '#insertStatement', 'insert #dependencies ');
set #sql = replace(#sql, '#server_name', #server_name);
exec (#sql);
-- Database loop terminations
if ##rowcount > 0
set #server_had_some_inserts = 1;
end -- database loop
-- server loop terminations
if #server_had_some_inserts = 0
begin
declare #remote_user_name nvarchar(255);
select #remote_user_name = remote_name
from sys.linked_logins li
join sys.servers s on li.server_id = s.server_id
where remote_name is not null
and s.name = 'sisag'
print (
'No dependencies found for ' + #server_name + '. ' +
'If this is unexpected, you may need to run "grant view any definition to ' +
'[' + isnull(#remote_user_name, '?') + ']" ' +
'on the remote server.'
);
end
end -- server loop
-- Terminate
select * from #dependencies
The code for AddBracketsWhenNecessary:
create function AddBracketsWhenNecessary (
#objectName nvarchar(250)
)
returns nvarchar(250) as
begin
if left(#objectName, 1) = '[' and right(#objectName, 1) = ']'
return #objectName;
declare #hasInvalidCharacter bit;
select #hasInvalidCharacter = max(isInvalid)
from dbo.splitString(#objectName, null) chars
cross apply (select
isLetter = patindex('[a-z,_]', val),
isNumber = PATINDEX('[0-9]', val)
) getCharType
cross apply (select
isInvalid =
case
when isLetter = 1 then 0
when isNumber = 1 and not chars.id = 1 then 0
else 1
end
) getValidity
return
case when #hasInvalidCharacter = 1 then '[' else '' end
+ #objectName
+ case when #hasInvalidCharacter = 1 then ']' else '' end;
end
Any finally, my splitter function (but see Arnold Fribble here if you want a simpler version, or use the built in function if you have SqlServer 2016 or above):
create function splitString (
#stringToSplit nvarchar(max),
#delimiter nvarchar(50)
)
returns table as
return
with
split_by_delimiter as (
select id = 1,
start = 1,
stop = convert(int,
charindex(#delimiter, #stringToSplit)
)
union all
select id = id + 1,
start = newStart,
stop = convert(int,
charindex(#delimiter, #stringToSplit, newStart)
)
from split_by_delimiter
cross apply (select newStart = stop + len(#delimiter)) ap
where Stop > 0
),
split_into_characters as (
select id = 1,
chr = left(#stringToSplit,1)
union all
select id = id + 1,
chr = substring(#stringToSplit, ID + 1, 1)
from split_into_characters
where id < len(#stringToSplit)
)
select id,
val =
ltrim(rtrim(substring(
#stringToSplit,
start,
case
when stop > 0 then stop - start
else len(#stringtosplit)
end
)))
from split_by_delimiter
where len(#delimiter) > 0
union all
select id,
val = chr
from split_into_characters
where #delimiter = ''
or #delimiter is null
I had to make some small changes from the real code I use, so if there are any reference errors, please let me know in the comments and I'll edit.

Answer 4

A Query I often use to find the tables used from other databases is the following:
SELECT OBJECT_NAME (referencing_id) AS referencing_object, referenced_database_name,
referenced_schema_name, referenced_entity_name
FROM sys.sql_expression_dependencies
WHERE referenced_database_name IS NOT NULL
AND is_ambiguous = 0;
This gives you all tables used in the stored procedures / views that origin from this database, but also other databases.
source

Answer 5

I upgraded one of the answer adding referencing/referenced id and referencing/referenced type like table, view, etc.
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[get_crossdatabase_dependencies] AS
SET NOCOUNT ON;
CREATE TABLE #databases(
database_id int,
database_name sysname
);
INSERT INTO #databases(database_id, database_name)
SELECT database_id, [name]
FROM sys.databases
WHERE 1 = 1
AND [state] <> 6 /* ignore offline DBs */
AND database_id NOT IN (4, 5, 6, 7, 11, 13, 14); /* ignore system DBs */
DECLARE
#database_id int,
#database_name sysname,
#sql varchar(max);
CREATE TABLE #dependencies(
referencing_id int,
referencing_database varchar(max),
referencing_schema varchar(max),
referencing_object_name varchar(max),
referencing_type varchar(max),
referenced_id int,
referenced_server varchar(max),
referenced_database varchar(max),
referenced_schema varchar(max),
referenced_object_name varchar(max),
referenced_type varchar(max),
);
WHILE (SELECT COUNT(*) FROM #databases) > 0 BEGIN
SELECT TOP 1 #database_id = database_id,
#database_name = database_name
FROM #databases;
SET #sql = 'INSERT INTO #dependencies select
referencing_id,
DB_NAME(' + convert(varchar,#database_id) + '),
OBJECT_SCHEMA_NAME(referencing_id,'
+ convert(varchar,#database_id) +'),
OBJECT_NAME(referencing_id,' + convert(varchar,#database_id) + '),
CASE
WHEN OBJECTPROPERTY(referencing_id, ''IsTable'') = 1 THEN ''Table''
WHEN OBJECTPROPERTY(referencing_id, ''IsView'') = 1 THEN ''View''
WHEN OBJECTPROPERTY(referencing_id, ''IsProcedure'') = 1 THEN ''Procedure''
WHEN OBJECTPROPERTY(referencing_id, ''IsTableFunction'') = 1 THEN ''Table-valued Function''
ELSE ''Unknown''
END AS referencing_type,
referenced_id,
referenced_server_name,
ISNULL(referenced_database_name, db_name('
+ convert(varchar,#database_id) + ')),
referenced_schema_name,
referenced_entity_name,
CASE
WHEN OBJECTPROPERTY(referenced_id, ''IsTable'') = 1 THEN ''Table''
WHEN OBJECTPROPERTY(referenced_id, ''IsView'') = 1 THEN ''View''
WHEN OBJECTPROPERTY(referenced_id, ''IsProcedure'') = 1 THEN ''Procedure''
WHEN OBJECTPROPERTY(referenced_id, ''IsTableFunction'') = 1 THEN ''Table-valued Function''
ELSE ''Unknown''
END AS referenced_type
FROM ' + quotename(#database_name) + '.sys.sql_expression_dependencies
ORDER BY
referencing_type';
EXEC(#sql);
DELETE FROM #databases WHERE database_id = #database_id;
END;
SET NOCOUNT OFF;
SELECT * FROM #dependencies;