Abstract: Columns of a non-relational data store may be efficiently dropped. A drop column request for a table stored in a non-relational database may be received. In response to the drop column request, schema information for the table may be updated to filter out the column from subsequent read responses to read requests. A backup of the table is created and evaluated to identify those items in the table that include the column. The column is then deleted from the identified items.

Abstract: Methods and apparatus for client-directed placement of remotely configured service instances are described. One or more placement target options are selected for a client of a network-accessible service based on criteria such as service characteristics of the placement targets. The selected options, including a particular placement target that includes instance hosts configurable from remote control servers, are indicated programmatically to the client. A determination is made that a service instance is to be configured at the particular placement target on behalf of the client. A remote control server is configured to issue administrative commands to an instance host at the particular placement target to configure the service instance.

Abstract: Methods and apparatus for client-directed placement of remotely configured service instances are described. One or more placement target options are selected for a client of a network-accessible service based on criteria such as service characteristics of the placement targets. The selected options, including a particular placement target that includes instance hosts configurable from remote control servers, are indicated programmatically to the client. A determination is made that a service instance is to be configured at the particular placement target on behalf of the client. A remote control server is configured to issue administrative commands to an instance host at the particular placement target to configure the service instance.

Abstract: A distributed database management system comprises a plurality of peers and maintains data on behalf of a plurality of clients. Upon receiving a request to access data, the distributed database management system identifies, from among the plurality of peers, a set of peers associated with the client issuing the request. The distributed database management system provides, to the client, a list of the set of identified peers. Access to data maintained by the distributed database system is based, at least in part, on connections between the client and the set of identified peers.

Abstract: A distributed database system maintains data for a logical table by storing, on a plurality of storage nodes, a collection of key-item pairs. The distributed database system receives a query of the logical table, and identifies one or more portions of a key specified by the query. Based on the one or more portions of the key, the distributed database causes at least one of a get, range query, or scan operation to be performed by one or more of the storage nodes. Results for the query are generated based on one or more items obtained by performance of the operation.

Abstract: A distributed database system maintains data for a database client by storing data on a plurality of storage nodes. Upon receiving a request from the database client in a first format, the database system translates the request to a second format and sends the translated request to a storage subsystem. The storage subsystem generates an exception if the translated request cannot be successfully completed. The distributed database system resends the translated request on behalf of the database client if the exception corresponds to a request that can be retried, and continues to resend the translated request until a first of an expiration of a predetermined time period or until the request completes successfully. The distributed database system sends a response to the database client based on the resent database request.

Abstract: A distributed database system maintains data for a logical table by storing, on a plurality of storage nodes, a collection of key-item pairs. An operation to delete a range of these items is processed by first storing, on each of the plurality of storage nodes, a tombstone record indicative of the items to be deleted. The tombstones are committed once each of the plurality of nodes has stored the tombstone. Items within the range are treated as deleted. A cleanup operation deletes items within the range and updates the tombstone.

Abstract: A service implements techniques for modifying a data table stored in a key-value or non-relational database via a table-oriented schema. In some aspects, a request to modify a table-oriented schema of a table of data may be received. In response to the request, an association between a customer identifier of elements of the table and an internal identifier of elements of the table may be stored that updates a prior association between a customer identifier and an internal identifier. The table-oriented schema of the table may be modified using one or more keys that are generated using the internal identifier.

Abstract: A data storage service implements encoding techniques for generating compound partition keys, compound clustering keys, or a combination for more flexibility in storing data in a key-value database system. In some aspects a request to store data with multiple partition keys and/or multiple clustering keys may be received. Length information may be added to the partition keys, and the results concatenated together to form a compound partition key used to store the data in the database. Ordering information may be added to the clustering keys, and the results concatenated together to form a compound clustering key, to be used in storing and sorting data in the database. In some cases, the clustering keys may be made a uniform length, such as by padding keys, as necessary, to have a length that is a multiple of an arbitrary number, and then dividing the clustering keys into chunks of that arbitrary number.

Abstract: Methods and apparatus for client-directed placement of remotely configured service instances are described. One or more placement target options are selected for a client of a network-accessible service based on criteria such as service characteristics of the placement targets. The selected options, including a particular placement target that includes instance hosts configurable from remote control servers, are indicated programmatically to the client. A determination is made that a service instance is to be configured at the particular placement target on behalf of the client. A remote control server is configured to issue administrative commands to an instance host at the particular placement target to configure the service instance.

Abstract: Methods and apparatus for client-directed placement of remotely configured service instances are described. One or more placement target options are selected for a client of a network-accessible service based on criteria such as service characteristics of the placement targets. The selected options, including a particular placement target that includes instance hosts configurable from remote control servers, are indicated programmatically to the client. A determination is made that a service instance is to be configured at the particular placement target on behalf of the client. A remote control server is configured to issue administrative commands to an instance host at the particular placement target to configure the service instance.

Abstract: Systems and methods for providing on-demand diagnostics in a virtual environment are disclosed. In one embodiment, a method comprises storing a list of approved diagnostic tests. A diagnostic service can be running in the multi-tenant environment. The diagnostic service can receive a request to run a selected diagnostic test from the list of approved diagnostic tests on one or more hardware resources in the virtual environment. In response to the request, the selected diagnostic test can be transmitted to the one or more hardware resources.