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Limits in Amazon DynamoDB
Following is a table that describes current limits within Amazon DynamoDB (or no limit, in some cases, for your information).
| Table name | Allowed characters are a-z, A-Z, 0-9, '_' (underscore), '-' (dash), and '.' (dot). Names can be between 3 and 255 characters long. |
| Table size | No limit in number of bytes or items. |
| Tables per account | By default, the number of tables per account is limited to 256. However, you can request an increase in this limit. For more information, go to Amazon DynamoDB Limit Increase Form. |
| Provisioned Throughput |
DynamoDB is designed to scale without limits. However, if you wish to exceed throughput rates of 10,000 write capacity units or 10,000 read capacity units for an individual table, you can request an increase in these limits. For more information, go to Amazon DynamoDB Limit Increase Form. By default, there is a limit of 20,000 write capacity units or 20,000 read capacity units per account. However, you can request an increase in these limits using the same form. |
| Provisioned Throughput minimum per table | 5 ReadCapacityUnits and 5 WriteCapacityUnits. |
| UpdateTable provisioned throughput change minimum (reduction or increase) | If either ReadCapacityUnits or WriteCapacityUnits is reduced or increased, it must change by at least 10%. |
| UpdateTable provisioned throughput reduction frequency maximum | Once per UTC calendar day. If you decrease either ReadCapacityUnits or WriteCapacityUnits, the one reduction counts as your table's allowed decrease for that day. You can decrease both values at the same time in the same UpdateTable request, but not each value, separately, in a single day. |
| UpdateTable provisioned throughput increase maximum | If either ReadCapacityUnits or WriteCapacityUnits is increased, it can only be increased up to twice the current value. |
| UpdateTable provisioned throughput increase frequency maximum | No limit. |
Maximum concurrent Control Plane API requests (includes cumulative number
of tables in the CREATING or
DELETING state) | 10. Except, you can have only one table in the
UPDATING state at a time. |
| Item size | Cannot exceed 64KB which includes both attribute name binary length (UTF-8 length) and attribute value lengths (again binary length). The attribute name counts towards the size limit. For example, consider an item with two attributes: one attribute named "shirt-color" with value "R" and another attribute named "shirt-size" with value "M". The total size of that item is 23 bytes. |
| Attribute name (for primary key attributes only) | Names must be between 1 and 255 characters long, inclusive. They can be any UTF-8 encodable character, and the total size of the UTF-8 string after encoding can't exceed 255 bytes. |
| Attribute values | Attribute values cannot be null or empty. |
| Attribute name-value pairs per item | The cumulative size of attributes per item must be under 64KB. |
| Hash primary key attribute value | 2048 bytes |
| Range primary key attribute value | 1024 bytes |
| String | All strings must conform to the UTF-8 encoding. Since UTF-8 is a variable width encoding, string sizes are determined using the UTF-8 bytes. |
| Number | A number can have up to 38 digits precision and can be between 10^-128 to 10^+126. |
| Maximum number of values in a String Set or Number Set | No limit on the quantity of values, as long as the item containing the values fits within the 64KB item limit. |
