In case of a persistent partitioned region, what data is stored in the associated disk-store on ANY ONE MEMBER. Is it all the data for the region including those held on other members, or is it just the primary data THE MEMBER is hosting, or is it the primary and any redundant data THE MEMBER is hosting.
The data in the disk store is just the primary and redundant data that the member is hosting, not all of the data for the region.
Related
Let's say I have 3 PARTITIONED_REDUNDANT regions:
/Orders - keys are Longs (an ID allocated from /Sequences) and values are instances of Order
/OrderLineItems - keys are Longs (an ID allocated from /Sequences) and values are instances of OrderLineItem
/Sequences - keys are Strings (name of a sequence), values are Longs
The /Sequences region will have many entries, each of which is the ID sequence for some persistent type of that is stored in another region (e.g., /Orders, /OrderLineItems, /Products, etc.)
I want to run a Geode transaction that persists one Order and a collection of OrderLineItems together.
And, I want to allocate IDs for the Order and OrderLineItems from the entries in the /Sequences region whose keys are "Orders" and "OrderLineItems", respectively. This operates like an "auto increment" column would in a relational database - the ID is allocated/assigned at insertion time as part of the transaction.
The insertion of Orders and OrderLineItems and the allocation of IDs from the /Sequences region need to be transactionally consistent - they all succeed or fail together.
I understand that Geode requires data being operated on in transaction to be co-located if the region is partitioned.
The obvious thing is to co-locate OrderLineItems with the owning Order, which can be done with a PartitionResolver that returns the Order's ID as the routing object.
However, there's still the /Sequences region that is involved in the transaction, and I'm not clear on how to co-locate that data with the Order and OrderLineItems.
The "Orders" entry of the /Sequences reqion would need to be co-located with every Order for which an ID is generated...wouldn't it? Obviously that's not possible.
Or is there another / better way to do this (e.g., change region type for /Sequences)?
Thanks for any suggestions.
Depending on how much data is in your /Sequences region - you could make that region a replicated region. A replicated region is considered co-located with all other regions because it's available on all members.
https://geode.apache.org/docs/guide/15/developing/transactions/data_location_cache_transactions.html
This pattern is potentially expensive though if you are creating a lot of entries concurrently. Every create will go through these shared global sequences. You may end up with a lot of transaction conflicts, especially if you are getting the next sequence number by incrementing the last used sequence number.
As an alternative you might want to consider UUIDs as the keys for your Orders and OrderLineItems, etc. A UUID takes twice as much space as a long, but you can allocate a random UUID without needing any coordination between concurrent creates.
I'm hoping to keep common data from the same user partitioned together. Normally I'd just use the same partition key to accomplish that but in this case the data is in different tables. E.g users, photos, friends, etc
I have seen it explicitly stated but I assume that even if I use the partition key across tables that I won't be able to accomplish this. Can anyone validate or disprove?
Data with the same partition key but in different tables has no guarantee of being on the same server. If you check out the Storage Table Design Guide, particularly the section titled 'Table Partitions', you'll find 'The account name, table name and PartitionKey together identify the partition within the storage service where the table service stores the entity.' That guide may help you clarify this question and anything related.
I'm developing system that manages objects consisting of components. What would the best way to store them in SQLITE database from performance point of view? if there are 20 component types
each component is a blob 1-10Kb size. Typically each object consists of 4-6 different components.
I can see two options:
Implement it as one table with key and 20 blob columns
Use 20 tables with key and single blob column
The only queries I will make to database are: get component data by id, write data and remove data.
PS: object class looks like this:
class Entity
{
Component *components[20];
}
usually components array have 4-6 not null pointers
You will probably want an Entity Attribute Value structure to store the BLOBs.
CREATE TABLE myObjectComponents (
objectID INTEGER, -- Entity
componentTypeID INTEGER, -- Attribute
componentBLOB BLOB, -- Value
PRIMARY KEY objectID, componentTypeID
)
You can then also add a traditional "myObject" table with other non-blob values (Such as it's identity column, owner, name, creation and modified timestamps, etc, etc), and enforce integrity with foreign key constraints.
EAV tables are very flexible and good for fast look-up of the Value column.
They're very poor in the other direction; "given a Value (or combination of values), which Entities have it?" But you don't seem likely to be searching a BLOB field.
You may want to read more about the merits and dis-advantages of EAV, there are plenty of references on-line.
The benefit of this structure in your case is that each row only has one BLOB and (possibly more importantly) it isn't sparsely populated; You won't have rows with capacity for 20 BLOBs but only use, for example, four of those. This will make it easier to transfer the relevant rows around in memory.
I am creating a data warehouse from a store database and I have a question regarding the design of my dimensions and facts.
In the store database a table exists for Person, Person_Address and Person_Address_Type. These are linked by another tabled name Entity_Address_ID which links the three tables by their primary keys to give details on what a person's address is and what type of address it is.
My question is, should I create a dimension for all three tables, and a fact-less fact table to link them together or should I de-normalise my dimensions and add to each dimension a foreign key for the address and address type they are linked too?
Here is a very quick UML of what the current database looks like to provide clarification
You should create a Person dimension with a set of address attributes (mailing address, billing address, etc), i.e. denormalize all this data and load it into a single table.
there is no possibility to store one data files in to two table space.but when creating IOT in oracle we are giving over flow property to another table space!
usually data file contains tables even IOT see this image Click for concept here!so how can point out two tablespace for pointing one table(IOT).let is consider the following code:
CREATE TABLE admin_docindex(
token char(20),
doc_id NUMBER,
token_frequency NUMBER,
token_offsets VARCHAR2(2000),
CONSTRAINT pk_admin_docindex PRIMARY KEY (token, doc_id))
ORGANIZATION INDEX
TABLESPACE admin_tbs
PCTTHRESHOLD 20
OVERFLOW TABLESPACE admin_tbs2;
One segment in Oracle will be stored in exactly one tablespace. But one object may be comprised of many different segments. For example, if you have a partitioned table, each partition is a separate segment each of which may be stored in a different tablespace. Each LOB in a table is a separate segment that can potentially be stored in a different tablespace. And, in your case, the row overflow area is a separate segment from the segment storing the main table segment.
The various scenarios where a table can comprise multiple segments was discussed over on the DBA stack yesterday.