tree-like structure, which represents the overall execution plan. The plan represents each operator as a node in the tree. Each operator takes as input zero or more rows, and produces as output zero or more rows Topology Service, and in some cases are also able to evaluate expression values locally. Each leaf node will not have input from other operators, and pipe in any nodes they produce into their parent nodes The parents nodes will then pipe in nodes to their parent nodes, all the way up to a root node. The root node produces the final results of the query and delivers the results to the user. Observing Execution

Topology Service must also support a Watch interface, to signal when certain conditions occur on a node. This is used, for instance, to know when the Keyspace topology changes (e.g. for resharding). Global of a server, and by the root node path to put the Vitess data in (it cannot start with /). For instance, assuming we want to use servers global_server:global_port with node path vitess/global: # Set the still needs to be created, just use the same server address and, very importantly, a different root node path. Implementation details For locks, we use a file named Lock in the directory to lock, and the

Topology Service must also support a Watch interface, to signal when certain conditions occur on a node. This is used, for instance, to know when the Keyspace topology changes (e.g. for resharding). Global of a server, and by the root node path to put the Vitess data in (it cannot start with /). For instance, assuming we want to use servers global_server:global_port with node path vitess/global: # Set the still needs to be created, just use the same server address and, very importantly, a different root node path. Implementation details For locks, we use a file named Lock in the directory to lock, and the

tree-like structure, which represents the overall execution plan. The plan represents each operator as a node in the tree. Each operator takes as input zero or more rows, and produces as output zero or more rows Topology Service, and in some cases are also able to evaluate expression values locally. Each leaf node will not have input from other operators, and pipe in any nodes they produce into their parent nodes The parents nodes will then pipe in nodes to their parent nodes, all the way up to a root node. The root node produces the final results of the query and delivers the results to the user. 19 Observing

tree-like structure, which represents the overall execution plan. The plan represents each operator as a node in the tree. Each operator takes as input zero or more rows, and produces as output zero or more rows Topology Service, and in some cases are also able to evaluate expression values locally. Each leaf node will not have input from other operators, and pipe in any nodes they produce into their parent nodes The parents nodes will then pipe in nodes to their parent nodes, all the way up to a root node. The root node produces the final results of the query and delivers the results to the user. Observing Execution

tree-like structure, which represents the overall execution plan. The plan represents each operator as a node in the tree. Each operator takes as input zero or more rows, and produces as output zero or more rows Topology Service, and in some cases are also able to evaluate expression values locally. Each leaf node will not have input from other operators, and pipe in any nodes they produce into their parent nodes The parents nodes will then pipe in nodes to their parent nodes, all the way up to a root node. The root node produces the final results of the query and delivers the results to the user. Observing Execution

tree-like structure, which represents the overall execution plan. The plan represents each operator as a node in the tree. Each operator takes as input zero or more rows, and produces as output zero or more rows Topology Service, and in some cases are also able to evaluate expression values locally. Each leaf node will not have input from other operators, and pipe in any nodes they produce into their parent nodes The parents nodes will then pipe in nodes to their parent nodes, all the way up to a root node. The root node produces the final results of the query and delivers the results to the user. Observing Execution

tree-like structure, which represents the overall execution plan. The plan represents each operator as a node in the tree. Each operator takes as input zero or more rows, and produces as output zero or more rows Topology Service, and in some cases are also able to evaluate expression values locally. Each leaf node will not have input from other operators, and pipe in any nodes they produce into their parent nodes The parents nodes will then pipe in nodes to their parent nodes, all the way up to a root node. The root node produces the final results of the query and delivers the results to the user. Observing Execution

error: HttpResponseNotOkError: [status 500] /api/keyspaces: unknown rpc error: code = Unknown desc = node doesn't exist: /vitess/global/keyspaces/KEYSPACE_NAME/Keyspace If a single keyspace returns an error