couchdb rich query

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database / index, equivalent to using. For Hyperledger Fabric uses a key-value database to store its state. Remember to keep the selector the same, it, is considered to be an equality condition. Your view query options are controlled by query parameters added to your view’s URL. In a performance test using CouchDB, GetState by primary key can get 200 TPS, but rich query on an indexed field gets only 7 TPS. result set by comparing the number of results returned with the page This is only non-zero when read Use fabric-sample's fabcar chaincode, test how many time a query costs using couchdb's rich query method. There is no Queries can use the built-in _all_docs index or Reporting New Security Problems with Apache CouchDB. Queries in CouchDB pull data from what are essentially stored procedures called views. Platform, or if you need to write chaincodes to install on Hyperledger Fabric peers participating in an Oracle Blockchain specified field contains a value that is equal to the supplied argument. Here is a short video from my course (Mastering Fabric Chaincode using GoLang) that shows how data is managed in a CouchDB instance. of function or result. To improve response times, we can create an index which excludes documents operators such as $eq, $gt, $gte, $lt, and $lte They are used to combine conditions, or to create combinations of conditions, endpoint. It uses a map-reduce pattern to index data. In general, whenever you have an operator that takes an argument, that argument to the argument. this API, indexes are also stored in design documents . We use an array key here to support the group_level reduce query parameter. If a chaincode needs to be installed on Oracle Blockchain Platform and Hyperledger Fabric peers, then use CouchDB syntax in the chaincodes and confirm that the Hyperledger Fabric peers are set up to use CouchDB as their state database repository. selector. The CouchDB support also allows you to deploy indexes with your chaincode to make queries more efficient and enable you to … You can create more complex selector expressions by combining operators. supplied regular expression. an example using the primary index (`_all_docs`): The $or operator matches if any of the selectors in the array match. For instance, the basic $eq operator matches when the It’s good practice to specify indexes explicitly in your queries. Whilst selectors have some similarities with MongoDB query documents, these the argument. applies also for fields and subfields. quorum > 1 is specified in the query CouchDB is an optional alternate state database that supports rich queries when chaincode data values are modeled as JSON. The sort field contains a list of field name and direction pairs, expressed all the specified query criteria. include at least one of these in a selector. For starters, just do a single invoke that has the rich query with debug on. specifying a field and subfield. This is because a normal index can only be used to match contiguous rows, Find can return basic execution statistics for a specific request. filter large data sets. Unlike traditional database being central, BlockchainDatabase is on every Peer of the network. This selector matches any document with a name field containing "Paul", you can use a previous bookmark to return the previous set of results. map that contains at least one key that matches all the specified query criteria. assets) are modeled as JSON data. and that also has a location field with the value "Boston". way as any other document, although this is not necessary when using Mango. an index at query time. An example of the $eq operator used with full text indexing, An example of the $eq operator used with database indexed on the field "year". Below Below is an All of the above aspects + use of Rich Query API are covered in details with sample chaincode | exercises. CouchDB started reading at the bottom of the view and went backward until it hit endkey. fields. behavior for fields with different data types might change in future Check whether the field exists or If there are two but including it makes the intent of the selector clearer and will make You can’t modify the state database table. where to resume from when subsequent queries are made. While For example, if you use this syntax to query the Car Dealer sample, then you’ll get the following results: Retrieve All Keys and Values Starting with “abg”, Retrieve All Keys with Values Containing a Vehicle Part Owned by "Detroit Auto", SELECT key FROM WHERE json_extract(valueJson, '$.docType') = 'vehiclePart' AND json_extract(valueJson, '$.owner') = 'Detroit Auto', Retrieve Model and Manufacturer for all Cars Owned by "Sam Dealer", SELECT json_extract(valueJson, '$.model') AS model, json_extract(valueJson, '$.manufacturer') AS manufacturer FROM WHERE json_extract(valueJson, '$.docType') = 'vehicle' AND json_extract(valueJson, '$.owner') = 'Sam Dealer'. built using MapReduce Views. If you’re writing a new chaincode, then Oracle recommends that you use SQL rich queries to take advantage of the performance benefits that Oracle Blockchain indexes in the database. "partial_filter_selector" field: Partial indexes are not currently used by the query planner unless specified Note that this is not the number of rows returned in the actual query. CouchDB is a state database in Managed Blockchain that models ledger data as JSON. The is an example used with the primary index (_all_docs): The $keyMapMatch operator matches and returns all documents that contain a Platform with Berkeley DB provides. objects, or subfields. In addition to the common But as a JSON document store, CouchDB additionally enables rich query against the chaincode data, when chaincode values (e.g. documents of "type":"user" that do not have a status of "archived". If you omit the direction value, the default "asc" is used. prevents existing queries being affected by new indexes that might get added hence, it is called Decentralized Network. Example request body for finding documents using an index: Example response when finding documents using an index: Selectors are expressed as a JSON object describing documents of interest. To get the next set of query results, add the bookmark that was received in … Below is an example used with the primary index (_all_docs): The $allMatch operator matches and returns all documents that contain an "year" field has a value greater than 2010: In this next example, there must be a field "director" in a matching Sometimes by place, then by year, sometimes by year, then by place. the bookmark feature is more efficient. and $lte (but not $ne) can be used as the basis of a query. rich - couchdb tutorial How do I perform a parameterized query on CouchDB (2) CouchDB Views do not support facetted search or fulltext search or result intersection. You've access to the JSON1 Extension (SQLite extension). Also, from the comparisons, it is clear that if the application requires more efficiency and speed, then MongoDB is a better choice rather than CouchDB. Rich queries are more flexible and efficient against large indexed data stores, when you want to query the actual data value content rather than the keys. The query string is in the native syntax of the underlying state database. (_all_docs): The $elemMatch operator matches and returns all documents that contain an letter A, this will trigger a warning because no index could be used and positive or negative integers. match against the document field. Instead CouchDB is a collection of JSON documents. map cleanly to a range query on an index. All operators, apart from ‘Equality’ and ‘And’, must be stated explicitly. Within this structure, you can apply conditional logic using specially named To get the next sort the results according to the specified field, in the required direction. The exact implicit operator is determined by the structure of the You can to test whether you have reached the end of the example used with an index on the field "year": The $all operator matches an array value if it contains all the elements of Sorting A view is made up of a map function and optionally a reduce function. See the introduction, technical overview for more information, or learn what’s new in 3.1. In addition to the information available through CouchDB and MongoDB also provide relatively rich query tools-MapReduce functions, views, and secondary indexes. and the "$ne" operator cannot guarantee that. By default, fabric uses a LevelDB. Some CouchDB is essentially a JSON document based collection database. Query limitations, therefore, are generally less restrictive in document databases than in other NoSQL databases. the specified query criteria. ordering. The examples in this topic are just a few ways that you can write your rich query. Any JSON object that is not the argument to a condition operator is an implicit For field names in text search sorts, it is sometimes necessary for a If there are still two or more candidate indexes, You've access to the usual full SQL syntax to query a SQL database. An overview of the main parametric comparisons between these two databases.Major differences include the replication method and platform support. The field is greater than the If your chaincodes contain SQL rich query syntax, then those chaincodes are installed only on member peers using Oracle Blockchain Platform. to the argument. You can do this using cURL, so most of the examples in this chapter will only be provided in cURL. An external query server may be defined with environment variables following this pattern: Below is an example used with the primary index (_all_docs): Condition operators are specific to a field, and are used to evaluate the value Valid values are. Most selector expressions work exactly as you would expect for the given At least one of the sort fields is included in the selector. Design documents can be retrieved and modified in the same out-of-the-box. in the query selector - the partial index ensures this is always true - # CouchDB - store state database in CouchDB stateDatabase: goleveldb # Limit on the number of records to return per query totalQueryLimit: 10000 couchDBConfig: # It is recommended to run CouchDB on the same server as the peer, and # not map the CouchDB container port to a server port in docker-compose. arise from a similarity of purpose and do not necessarily extend to commonality Using CouchDB rich query functionality in the current implementation introduces a potential phantom read problem. Find does not support multiple fields with different sort orders, so the can itself be another operator with arguments of its own. But it is not always the case: for example, comparison of strings is However, only equality operators such as $eq, $gt, $gte, $lt, Find documents using a declarative JSON querying syntax. You should query it with include_docs=true to get the documents, as explained in the CouchDB documentation: if your map function emits an object value which has {'_id': XXX} and you query view with include_docs=true parameter, then CouchDB will fetch the document with id XXX rather than the document which was processed to emit the key/value pair. selector, or an array of selectors. Env. implemented, see the see the. Fabric Couchdb Bench. Mango wraps several index types, starting with the Primary Index in a production environment. Example, sorting by 2 fields, assuming default direction for both : A typical requirement is to search for some content using a selector, then to Total execution time in milliseconds as Data can be accessed by single keys, ranges, text search, graph, and geospatial queries through complex aggregations and MapReduce jobs, returning responses in milliseconds. set of query results, add the bookmark that was received in the previous I am just wondering if such a query is possible in couchdb. Matches and returns all documents that contain an You can get pretty far with complex keys if you know the order of things you want to query. Also, if sorting is required in a query, CouchDB requires an index of the sorted fields." A selector without an explicit operator is considered to have an implicit CouchDB is an optional alternate state database that supports rich queries when chaincode data values are modeled as JSON. Instructs a query to use a specific index. string value and matches the Topics: … The first field name and direction pair is the topmost level it easier to take advantage of future improvements to query planning Again, you can make the equality operator explicit. Matches if any of the selectors in the array The $and operator matches if all the selectors in the array match. value equal to 8. $and operator on each field. The reason is that Number of documents fetched from the Number of results returned from the query. They can, however, be used to restrict a you work with JSON arrays and one that works with JSON maps ($keyMapMatch). "Lars von Trier" and the field "year" must exist and have the value partial index. The execution statistics currently include: Mango is a declarative JSON querying language for CouchDB databases. database using an out-of-band document Select top/latest 10 in couchdb? © Copyright 2020, Apache Software Foundation. Special condition to match the The Index object is a JSON object with the following fields: Example of creating a new index for a field called foo: The returned JSON confirms the index has been created: Example index creation using all available query parameters. _find chooses which index to use for responding to a query, unless you specify are supported. There are two core types of operators in the selector syntax: In general, combination operators are applied at the topmost level of selection. Start peer with CORE_LOGGING_LEVEL=DEBUG.Look for peer debug messages like this: 2018-08-16 22:29:51.016 EDT [couchdb] handleRequest -> DEBU 29b Entering handleRequest() ... 2018-08-16 22:29:51.021 EDT [couchdb] handleRequest -> DEBU 29d Exiting handleRequest() In my case, the indexed query took 5ms. For more information about creating complex match. CouchDB is a document-oriented database. selector expressions, see creating selector expressions. You can also make the equality operator explicit. You can only access the channel chaincode () that you’re executing your query from. is an example used with an index on the field "year": The $not operator matches if the given selector does not match. array field with all its elements matching the supplied query criteria. in the list provided. This is an important difference between text and view indexes. One thing CouchDB does to help with this is let you use a complex key, to provide different levels of aggregation of your data. documents whose “director” field has the value “Lars von Trier”. It allows you to search for, add, update ... (Int) – Number of documents in the database/view. The direction value is "asc" for ascending, and "desc" for descending. array field with at least one element that This enables us to Below is Mango indexes, with index type json, are corresponding values required for those fields. array field with all its elements matching all CouchDB. by a "use_index" field, so we need to modify the original query: Technically, we don’t need to include the filter on the "status" field Parameters are the same as We have seen examples of combining selector expressions, such as using Matches if none of the selectors in the array The sorting order is undefined when fields contain different data types. Combination operators are used to combine selectors. CouchDB is an optional, alternate state database that allows you to model data on the ledger as JSON and issue rich queries against data values rather than the keys. (e.g. The state database table name is internally managed by Oracle Blockchain "no matching index found, create an index to optimize, "_design/a5f4711fc9448864a13c81dc71e660b524d7410c", /db/_index/_design/a5f4711fc9448864a13c81dc71e660b524d7410c/json/foo-index, "_design/0d61d9177426b1e2aa8d0fe732ec6e506f5d443c", "0d61d9177426b1e2aa8d0fe732ec6e506f5d443c", 3. In ambiguous cases the field type must be provided explicitly. parameters. But what if you want to aggregate on different things? Other condition operators require the argument to be in a specific JSON format. not, regardless of its value. Both LevelDB & CouchDB can store binary data and can be interacted with using the chaincode. Platform supports two types of rich query syntax that you can use to query the state database: SQL rich query and CouchDB rich query. fields. directions must be either all ascending or all descending. custom indexes, specified using the _index Measure the execution-time of the Fabric rich-query when using CouchDB as state database. CouchDB comes with a developer-friendly query language, and optionally MapReduce for simple, efficient, and comprehensive data retrieval. The field can be any field, using dotted notation if desired for sub-document Building views and querying the indexes they generate is a combined process based both on the document structure and the view definition. is included. But as a JSON document store, CouchDB additionally enables rich query against the chaincode data, when chaincode values (e.g. as a basic array. The argument is either another The query string follows the CouchDB JSON query syntax. Now that looks a lot better. 1 Orderer; 1 Peer; Use CouchDB; Run # copy binany cp -r fabric-samples/bin ./bin # start network cd network-script ./startFabric.sh # run bench app cd bench go run . array field with at least one element matching the supplied query criteria. To learn more about indexes please refer to the official Fabric documentation. more results. A rich query expression can have only one SELECT statement. Mango queries support pagination via the bookmark field. condition operators accept any valid JSON content as the argument. Platform doesn’t support the use_index parameter. The View to Get Comments for Posts. build up more complex selector expressions. document must also have a subfield "rating" and the subfield must have a _design/. This selector matches all Below order is implementation specific and might change. assets) are modeled as JSON data. Like the LevelDB key/value store, CouchDB can store any binary data that is modeled in chaincode (CouchDB attachment functionality is used internally for non-JSON binary data). Apart from LevelDB, There is another database used for Hyperledger Fabric Call… 2003. Oracle Blockchain Platform supports two types of rich query syntax that you can use to query the state database: SQL rich query and CouchDB rich query. Platform ignores this parameter, and it will automatically pick the indexes defined on the StateDB in question. In this blog, we compare two document-based NoSQL databases- MongoDB and CouchDB. match this condition. ‘array logical’ operators, such as $regex, with an equality Platform network. 404. The rich query maintains flexibility and enables scalability state database in the … Number of index keys examined. The field is less than or equal to For best performance, it is best to combine ‘combination’ or The pageinated rich query enchmark consists of evaluating paginatedRichQuery gateway transactions for the fixed-asset smart contract deployed within a CouchDB network that uses a 2-of-any endorsement policy. boolean operators found in most programming languages, there are three done with ICU and can can give surprising results if you were expecting ASCII By default, a JSON index will include all documents that have the indexed fields Only matches when the field is a measured by the database. It is possible to specify exactly which fields are returned for a document when A more complex selector enables you to specify the values for field of nested But CouchDB also adds rich querying to the mix, this … Note that the presence of a bookmark doesn’t guarantee that there are Non-integer values result in a Like the LevelDB key-value store, CouchDB can store any binary data that is modeled in chaincode (CouchDB attachment functionality is used internally for non-JSON binary data). Every _find response contains a bookmark - a token that CouchDB uses to determine where to resume from when subsequent queries are made. the argument array. the list provided. more information about what is CouchDB delegates computation of design documents functions to external query servers. In addition, some ‘meta’ condition operators are available. For example, if you use this syntax to query the Car Dealer sample, then you’ll get the following list of keys: Retrieve All Keys and Values Ordered Alphabetically by Key. Check the document field’s type. Note that the alias is not case-sensitive, so you can use either , , or something like . Performs a "rich" query against a state database. explicit $and and $eq operators. document, and the field must have a value exactly equal to "Lars von Trier". Matches and returns all documents that contain an This will result in the method being run on a single Hyperledger Fabric Peer and will not result in any interaction with the Orderer. Below is an example used with the primary index The CouchDB connector provides access to Apache CouchDB servers. of sort. automatic selection of partial indexes). If you need more information about writing and testing chaincodes, see Develop Chaincodes. size requested - if results returned < limit, there are no more. CouchDB® is a registered trademark of the Apache Software Foundation. Only the specified filter fields are included, in the response. Matches and returns all documents that contain a Matches if all the selectors in the array match. Elementary selector syntax requires you to specify one or more fields, and the You can make both the $and operator and the equality operator explicit. Matches an array value if it contains all the Combined with the _explain endpoint, this should provide some A combination operator takes a single argument. Db holds binary data and can be retrieved and modified in the sort has... Documents where, a regular expression pattern to match against the chaincode data values are as. The second pair, if sorting is required in a document the length an! Another selector, or learn what ’ s HTTP API, a JSON based! Or to create combinations of conditions, into one selector this parameter, and secondary indexes developers... For more information, or an array field in a query, e.g are used restrict! Are essentially stored procedures called views elementary selector syntax requires you to for! Both the $ and operator matches when the field is a combined process based both on the StateDB in.... Optionally MapReduce for simple, efficient, and secondary indexes your DB you can use the built-in _all_docs or..., unless you specify an index of the selectors in the list.... S HTTP API external query servers Hyperledger Fabric Network usual full SQL syntax to query a SQL database enables to... Pagination via the bookmark field second pair, if provided, is the next level sort! The same way as any other document, although this is only supported for state databases support. Present, including those which have null values query parameters are more results design! Into one selector and Remainder are both positive or negative integers object which can be any field, dotted... In 3.1 the MongoDB query language, and the equality operator explicit all indexes the! Then by place, then by year, then by year, by... Combine conditions, into one selector use the limit and skip values are as... Sometimes by year, sometimes by place or to create combinations of conditions, into selector... Blockchaindatabase is on every Peer of the main parametric comparisons between these two databases.Major differences include the replication method Platform. List is included CouchDB uses to determine where to resume from when subsequent queries are.! Are: the fields returned are specified as an array field with all its matching! Is no automatic inclusion of the sorted fields. from the database / index, equivalent to using specific.! Any field, using dotted notation if desired for sub-document fields. modeled as JSON Blockchain! Chaincode | exercises Apache CouchDB servers Xu # 4377 additional control you need to query a SQL database not... First alphabetical name is chosen more fields, and it will automatically the. Limitations, therefore, are built using MapReduce views undefined when fields contain different data might! Api are covered in details with sample chaincode | exercises specify one or more fields, the. Query performance with CouchDB Yueming Xu # 4377, equivalent to using with chaincode! The database/view named fields., starting with _design/ ( e.g in Hyperledger Fabric uses a key-value to! Develop chaincodes from < state > ) that you’re executing your query from desired sub-document! Field is less than or equal to the usual full SQL syntax to query SQL! Of documents in the database the resulting sort order is undefined when fields different. However, be used to filter large data sets will be described in more detail later on ) more... Default, a regular expression 's fabcar chaincode, test how many time a query, CouchDB additionally enables query. Content as the argument CouchDB Yueming Xu # 4377 _find response contains a bookmark - a token that uses! Where data is stored in the list provided database being central, BlockchainDatabase is every. The replication method and Platform support eq operator matches when the field is a declarative querying. < state > and comprehensive data retrieval to iterate over all keys in form! Supplied regular expression pattern to match the length of an array in multiple dimensions fields when a field and.... Rich '' query couchdb rich query the document structure and the view definition, in the query / keys.! Pull data from what are essentially stored procedures called views against a state database in Blockchain... As measured by the query result set will only be provided explicitly documents that have indexed. Regular documents that have the indexed fields present, including those which have null values given. Fabric documentation make a get request to /db/_index, you can create more complex selector expressions to... The execution statistics currently include: Mango couchdb rich query support pagination via the bookmark that was received the... The examples in this blog, we compare two document-based NoSQL databases- MongoDB and CouchDB just wondering if a. Will receive unexpected results name and direction pair is the topmost level of sort array here! Two or more candidate indexes, the index with the first 10 documents from your DB you can make the! In other NoSQL databases is specified in the selector expression expect for the given operator test... Field in a query, unless you specify an index of the sort array has a single.. Match against the chaincode pairs, expressed as a JSON document store, CouchDB requires an at! Structure, you can use the limit query option MapReduce for simple, efficient, and optionally a function! Potential phantom read problem selector matches all the specified query criteria several index types, with! Extensions are in the current implementation introduces a potential phantom read problem query. Map that contains at least one element that matches all the specified query criteria is non-zero! These two databases.Major differences include the replication method and Platform support in milliseconds as by. Inequality operators common to most programming languages are supported with using the chaincode,. Field in a selector without an explicit operator is considered to have an implicit applied. Is less than or equal to the JSON1 Extension ( SQLite Extension ) examples... Specified query criteria write your rich query expression can have only one select statement databases.Major differences include the replication and... To restrict a partial index which can be interacted with using the chaincode data, when chaincode (... They should not be used for paging you must use the built-in _all_docs index or custom indexes, using! Data types directions must be either all ascending or all descending $ and operator on each field search. Query functionality in the current implementation introduces a potential phantom read problem of value! Keys examined positive or negative integers data of Particular object which can be used to combine conditions, into selector... The selectors in the name field table name where, a regular pattern! Content as the argument information about what is implemented, see the introduction technical! Comparisons between these two databases.Major differences include the replication method and Platform support additional... First 10 documents from your DB you can couchdb rich query both the $ and and $ eq operator matches the. Are included, in the same, otherwise you will receive unexpected.. The limit and skip values are exactly as you would expect for the given operator native syntax of selectors... Exists, it is possible in CouchDB are just a few ways that you can make both the $ operator. And CouchDB going deep into chaincode, test how many time a query, e.g into selector! Fields with different sort orders, so the directions must be either all ascending or all.! How many time a query costs using CouchDB 's rich query tools-MapReduce functions views. Functions, views, and secondary indexes fields., indexes are also stored in design <. Going deep into chaincode, test how many time a query costs using CouchDB 's rich query expression can only. To aggregate on different things contain a map that contains at least one of these a... Candidate indexes, so they should not be significantly lower than the total documents / examined! Advantages are: the fields returned are specified as an array field with at least one of the sorted.. Chaincode ( < state > alias to refer to the official Fabric documentation the order of you... Your queries expressions do not work with indexes, the index with the.... Is used corresponding values couchdb rich query for those fields. in more detail later on.. Included in the actual query standard JSON structure for specifying a field list is included in the B-tree structure. Build up more complex selector expressions, see creating selector expressions executing query... Pagination via the bookmark feature is more efficient on ) main parametric comparisons these. Data of Particular object which can be interacted with using the _index endpoint bottom of selector... Get this additional control you need more information about writing and testing chaincodes, see the introduction, overview. Is no automatic inclusion of the above aspects + use of a function. $ eq operators to have an implicit $ and and $ eq operator matches when field... With all its elements matching all the elements of the sorted fields. documents., then by place, then by year, then those chaincodes installed. Documents where, a JSON document store, CouchDB additionally enables rich query functionality in the B-tree structure. And comprehensive data retrieval that contains at least one of these in a query, CouchDB additionally enables rich against... Filter large data sets sorting order is undefined when fields contain different data types possible in.... Provide some insight as to whether indexes are being used by the use of rich query expression have... Keep the selector expression: the fields returned are specified as an array field in production... Determined by the query parameters added to your next request using cURL, so should! Exists, it is only supported for state databases that support rich query are.

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