How to get attribute from a list of partition keys in DynamoDB - is scan my only option?
I've got a list of partition keys from one table.
userId["123","456","235"]
I need to get an attribute that they all share. like "username".
What would be the best practice to get them all at once?
Is scan my only option knowing that I know all my partition keys?
Do I know the sort key? yes but only the beginning of it. Therefore I
don't think I could use batchGetItem.
amazon-dynamodb
edited Nov 20 '18 at 23:56
John Rotenstein
74k782129
asked Nov 20 '18 at 23:20
adimonaadimona
3218
add a comment |
I've got a list of partition keys from one table.
userId["123","456","235"]
I need to get an attribute that they all share. like "username".
What would be the best practice to get them all at once?
Is scan my only option knowing that I know all my partition keys?
Do I know the sort key? yes but only the beginning of it. Therefore I
don't think I could use batchGetItem.
amazon-dynamodb
edited Nov 20 '18 at 23:56
John Rotenstein
74k782129
asked Nov 20 '18 at 23:20
adimonaadimona
3218
add a comment |
I've got a list of partition keys from one table.
userId["123","456","235"]
I need to get an attribute that they all share. like "username".
What would be the best practice to get them all at once?
Is scan my only option knowing that I know all my partition keys?
Do I know the sort key? yes but only the beginning of it. Therefore I
don't think I could use batchGetItem.
amazon-dynamodb
edited Nov 20 '18 at 23:56
John Rotenstein
74k782129
asked Nov 20 '18 at 23:20
adimonaadimona
3218
I've got a list of partition keys from one table.
userId["123","456","235"]
I need to get an attribute that they all share. like "username".
What would be the best practice to get them all at once?
Is scan my only option knowing that I know all my partition keys?
Do I know the sort key? yes but only the beginning of it. Therefore I
don't think I could use batchGetItem.
amazon-dynamodb
amazon-dynamodb
edited Nov 20 '18 at 23:56
John Rotenstein
74k782129
asked Nov 20 '18 at 23:20
adimonaadimona
3218
edited Nov 20 '18 at 23:56
John Rotenstein
74k782129
asked Nov 20 '18 at 23:20
adimonaadimona
3218
edited Nov 20 '18 at 23:56
John Rotenstein
74k782129
edited Nov 20 '18 at 23:56
John Rotenstein
74k782129
edited Nov 20 '18 at 23:56
John Rotenstein
74k782129
74k782129
asked Nov 20 '18 at 23:20
adimonaadimona
3218
asked Nov 20 '18 at 23:20
adimonaadimona
3218
asked Nov 20 '18 at 23:20
adimonaadimona
3218
3218
add a comment |
add a comment |
1 Answer
1
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oldest
votes
Scan is only appropriate if you don't know the partition keys. Because you know the partition keys you want to search, you can achieve the desired behavior with multiple Query operations.
A Query searches all documents with the specified partition key; you can only query one partition key per request, so you'll need multiple queries, but this will still be significantly more efficient than a single Scan operation.
If you're only looking for documents with a sort key that begins with something, you can include it in your KeyConditionExpression along with the partition key.
For example, if you wanted to only return documents whose sort key begins with a certain string, you could pass something like userId = :user_id AND begins_with(#SortKey, :str) as the key condition expression.
answered Nov 21 '18 at 0:30
Collin DauphineeCollin Dauphinee
10.7k12948
Thanks Collin, but wouldn't multiple queries be more expensive to run than just doing one scan?
– adimona
Nov 21 '18 at 0:45
1
No it won’t. A query only consumes RCU for items that match the key condition. Scan consumes RCU for everything in your table (or until you stop scanning).
– Matthew Pope
Nov 21 '18 at 2:34
add a comment |
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1 Answer
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active
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1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Scan is only appropriate if you don't know the partition keys. Because you know the partition keys you want to search, you can achieve the desired behavior with multiple Query operations.
A Query searches all documents with the specified partition key; you can only query one partition key per request, so you'll need multiple queries, but this will still be significantly more efficient than a single Scan operation.
If you're only looking for documents with a sort key that begins with something, you can include it in your KeyConditionExpression along with the partition key.
For example, if you wanted to only return documents whose sort key begins with a certain string, you could pass something like userId = :user_id AND begins_with(#SortKey, :str) as the key condition expression.
answered Nov 21 '18 at 0:30
Collin DauphineeCollin Dauphinee
10.7k12948
Thanks Collin, but wouldn't multiple queries be more expensive to run than just doing one scan?
– adimona
Nov 21 '18 at 0:45
1
No it won’t. A query only consumes RCU for items that match the key condition. Scan consumes RCU for everything in your table (or until you stop scanning).
– Matthew Pope
Nov 21 '18 at 2:34
add a comment |
Scan is only appropriate if you don't know the partition keys. Because you know the partition keys you want to search, you can achieve the desired behavior with multiple Query operations.
A Query searches all documents with the specified partition key; you can only query one partition key per request, so you'll need multiple queries, but this will still be significantly more efficient than a single Scan operation.
If you're only looking for documents with a sort key that begins with something, you can include it in your KeyConditionExpression along with the partition key.
For example, if you wanted to only return documents whose sort key begins with a certain string, you could pass something like userId = :user_id AND begins_with(#SortKey, :str) as the key condition expression.
answered Nov 21 '18 at 0:30
Collin DauphineeCollin Dauphinee
10.7k12948
Thanks Collin, but wouldn't multiple queries be more expensive to run than just doing one scan?
– adimona
Nov 21 '18 at 0:45
1
No it won’t. A query only consumes RCU for items that match the key condition. Scan consumes RCU for everything in your table (or until you stop scanning).
– Matthew Pope
Nov 21 '18 at 2:34
add a comment |
Scan is only appropriate if you don't know the partition keys. Because you know the partition keys you want to search, you can achieve the desired behavior with multiple Query operations.
A Query searches all documents with the specified partition key; you can only query one partition key per request, so you'll need multiple queries, but this will still be significantly more efficient than a single Scan operation.
If you're only looking for documents with a sort key that begins with something, you can include it in your KeyConditionExpression along with the partition key.
For example, if you wanted to only return documents whose sort key begins with a certain string, you could pass something like userId = :user_id AND begins_with(#SortKey, :str) as the key condition expression.
answered Nov 21 '18 at 0:30
Collin DauphineeCollin Dauphinee
10.7k12948
Scan is only appropriate if you don't know the partition keys. Because you know the partition keys you want to search, you can achieve the desired behavior with multiple Query operations.
A Query searches all documents with the specified partition key; you can only query one partition key per request, so you'll need multiple queries, but this will still be significantly more efficient than a single Scan operation.
If you're only looking for documents with a sort key that begins with something, you can include it in your KeyConditionExpression along with the partition key.
For example, if you wanted to only return documents whose sort key begins with a certain string, you could pass something like userId = :user_id AND begins_with(#SortKey, :str) as the key condition expression.
answered Nov 21 '18 at 0:30
Collin DauphineeCollin Dauphinee
10.7k12948
answered Nov 21 '18 at 0:30
Collin DauphineeCollin Dauphinee
10.7k12948
answered Nov 21 '18 at 0:30
Collin DauphineeCollin Dauphinee
10.7k12948
answered Nov 21 '18 at 0:30
Collin DauphineeCollin Dauphinee
10.7k12948
10.7k12948
Thanks Collin, but wouldn't multiple queries be more expensive to run than just doing one scan?
– adimona
Nov 21 '18 at 0:45
1
No it won’t. A query only consumes RCU for items that match the key condition. Scan consumes RCU for everything in your table (or until you stop scanning).
– Matthew Pope
Nov 21 '18 at 2:34
add a comment |
Thanks Collin, but wouldn't multiple queries be more expensive to run than just doing one scan?
– adimona
Nov 21 '18 at 0:45
1
No it won’t. A query only consumes RCU for items that match the key condition. Scan consumes RCU for everything in your table (or until you stop scanning).
– Matthew Pope
Nov 21 '18 at 2:34
Thanks Collin, but wouldn't multiple queries be more expensive to run than just doing one scan?
– adimona
Nov 21 '18 at 0:45
Thanks Collin, but wouldn't multiple queries be more expensive to run than just doing one scan?
– adimona
Nov 21 '18 at 0:45
1
1
No it won’t. A query only consumes RCU for items that match the key condition. Scan consumes RCU for everything in your table (or until you stop scanning).
– Matthew Pope
Nov 21 '18 at 2:34
No it won’t. A query only consumes RCU for items that match the key condition. Scan consumes RCU for everything in your table (or until you stop scanning).
– Matthew Pope
Nov 21 '18 at 2:34
add a comment |
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