Josh Berkus wrote:

You lost me on that one. What's a "vertical child table"?

Currently, you store data like this:

id      address uptime  speed   memory  tty
3       67.92   0.3             11.2            37              6
7       69.5            1.1             NULL    15              NULL
9       65.5            0.1             NULL    94              2

The most efficient way for you to store data would be like this:

main table
id      address
3       67.92
7       69.5
9       65.5

child table
id      value_type      value
3       uptime          0.3
3       speed           11.2
3       memory          37
3       tty                     6
7       uptime          1.1
7       memory          15
9       uptime          0.1
9       memory          94
9       tty                     2

As you can see, the NULLs are not stored, making this system much more efficient on storage space.

Tommorrow I'll (hopefully) write up how to query this for comparisons. It would help if you gave a little more details about what specific comparison you're doing, e.g. between tables or table to value, comparing just the last value or all rows, etc.

Got it. I can see how it would be more efficient in storing. At this point it would require a lot of query and code rewrites to handle it. Fortunately, we're looking for alternatives for the next revision and we're leaving ourselves open for a rewrite much to the boss's chagrin.

I will be spinning up a test server soon and may attempt a quick
implementation.  I may make value_type a foreign key on a table that
includes a full and/or brief description of the key.  Problem I'll have
then will be categorizing all those keys into disk, cpu, memory, user,
and all the other data categories since it's in one big table rather
than specialized tables.


Greg Spiegelberg
 Sr. Product Development Engineer
 Cranel, Incorporated.
 Phone: 614.318.4314
 Fax:   614.431.8388
Cranel. Technology. Integrity. Focus.

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