Now that looks a lot better. $and operator on each field. The implicit equality test CouchDB® is a registered trademark of the Apache Software Foundation. an index at query time. build up more complex selector expressions. CouchDB started reading at the bottom of the view and went backward until it hit endkey. Queries in CouchDB pull data from what are essentially stored procedures called views. CouchDB is a document-oriented database. You can create more complex selector expressions by combining operators. Design documents are regular documents that have an ID starting with Other condition operators require the argument to be in a specific JSON format. 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. Every _find corresponding values required for those fields. Query limitations, therefore, are generally less restrictive in document databases than in other NoSQL databases. Matches if any of the selectors in the array Using CouchDB rich query functionality in the current implementation introduces a potential phantom read problem. Platform, or if you need to write chaincodes to install on Hyperledger Fabric peers participating in an Oracle Blockchain hence, it is called Decentralized Network. all the specified query criteria. specified field contains a value that is equal to the supplied argument. The exact implicit operator is determined by the structure of the value equal to 8. Below Below is See the introduction, technical overview for more information, or learn what’s new in 3.1. Instead, you must use the alias to refer to the table name. include at least one of these in a selector. CouchDB allows a client to construct an almost arbitrarily rich response to a query with almost no restriction on how the data that should be included in that response. Only matches when the field is a To get the next set of query results, add the bookmark that was received in … Here is a short video from my course (Mastering Fabric Chaincode using GoLang) that shows how data is managed in a CouchDB instance. it, is considered to be an equality condition. For See. Matches if the given selector does not match. Writing an effective view to query your data may require changing or altering your document structure, or creating a more complex view in order to allow the specific selection of the data through the querying mechanism. Single Node Database. (but not $ne). Sorting 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 matching algorithms are based on offering significant performance improvements for query selectors that don’t We use an array key here to support the group_level reduce query parameter. to the argument. This selector matches any document with a name field containing "Paul", It has no rows or tables. CouchDB comes with a developer-friendly query language, and optionally MapReduce for simple, efficient, and comprehensive data retrieval. and $lte (but not $ne) can be used as the basis of a query. positive or negative integers. Note that the presence of a bookmark doesn’t guarantee that there are The argument is either another 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). A more complex selector enables you to specify the values for field of nested is included. operators such as $eq, $gt, $gte, $lt, and $lte the index with the first alphabetical name is chosen. By default, a JSON index will include all documents that have the indexed fields I am just wondering if such a query is possible in couchdb. fetch. Shows which index is being used by the query. is an example used with an index on the field "year": The $not operator matches if the given selector does not match. The MongoDB query language with rich secondary indexes enables developers to build applications that can query and analyze the data in multiple dimensions. For more information about creating complex Divisor and Remainder are both At least one of the sort fields is included in the selector. Data can be accessed by single keys, ranges, text search, graph, and geospatial queries through complex aggregations and MapReduce jobs, returning responses in milliseconds. For example, if you try to perform a query that attempts to match all documents arise from a similarity of purpose and do not necessarily extend to commonality response contains a bookmark - a token that CouchDB uses to determine Platform, {"docType": "vehiclePart", "serialNumber": "abg1234", "assembler": "panama-parts", "assemblyDate": 1502688979, "name": "airbag 2020", "owner": "Detroit Auto", "recall": false, "recallDate": 1502688979}, {"docType": "vehiclePart", "serialNumber": "abg1235", "assembler": "panama-parts", "assemblyDate": 1502688979, "name": "airbag 4050", "owner": "Detroit Auto", "recall": false, "recallDate": 1502688979}, {"docType": "vehiclePart", "serialNumber": "bra1238", "assembler": "bobs-bits", "assemblyDate": 1502688979, "name": "brakepad 4200", "owner": "Detroit Auto", "recall": false, "recallDate": 1502688979}, {"docType": "vehicle", "chassisNumber": "dtrt10001", "manufacturer": "Detroit Auto", "model": "a coupe", "assemblyDate": 1502688979, "airbagSerialNumber": "abg1235", "owner": "Sam Dealer", "recall": false, "recallDate": 1502688979, {"docType": "vehiclePart", "serialNumber": "ser1236", "assembler": "panama-parts", "assemblyDate": 1502688979, "name": "seatbelt 10020", "owner": "Detroit Auto", "recall": false, "recallDate": 1502688979}, {"docType": "vehiclePart", "serialNumber": "abg1234", "assembler": "panama-parts", "assemblyDate": "1502688979", "name": "airbag 2020", "owner": "Detroit Auto", "recall": "false", "recallDate": "1502688979"}, {"docType": "vehiclePart", "serialNumber": "abg1235", "assembler": "panama-parts", "assemblyDate": "1502688979", "name": "airbag 4050", "owner": "Detroit Auto", "recall": "false", "recallDate": "1502688979"}. Expression (PCRE) library. The View to Get Comments for Posts. Valid values are. Matches an array value if it contains all the The two advantages are: The fields returned are specified as an array. more results. The second pair, if provided, is the next level of sort. Number of documents fetched from the This enables us to Currently always 0. Find documents using a declarative JSON querying syntax. where "status": { "$ne": "archived" } at index time using the Platform, so you don't need to know the state database’s physical name when you write a chaincode. A selector without an explicit operator is considered to have an implicit in a production environment. Select top/latest 10 in couchdb? built using MapReduce Views. If there are two 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. The direction value is "asc" for ascending, and "desc" for descending. 404. This is because a normal index can only be used to match contiguous rows, Below Mango indexes, with index type json, are match. Matches documents where, A regular expression pattern to custom indexes, specified using the _index to the argument. the _explain endpoint, this should provide some automatic selection of partial indexes). 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. are supported. examined. result set by comparing the number of results returned with the page CouchDB is an optional alternate state database that supports rich queries when chaincode data values are modeled as JSON. How to Refer to the State Database in Queries. Both LevelDB & CouchDB can store binary data and can be interacted with using the chaincode. The state database table name is internally managed by Oracle Blockchain It is possible to specify exactly which fields are returned for a document when This CouchDB is an optional alternate state database that supports rich queries when chaincode data values are modeled as JSON. The reason is that present, including those which have null values. in production. selector expressions, see creating selector expressions. You can only access the channel chaincode () that you’re executing your query from. # 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. versions. See Table 4-1 for a list of This selector matches all This is an important difference between text and view indexes. Elementary selector syntax requires you to specify one or more fields, and the 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). While the database performs a full scan of the primary index: It’s always recommended that you create an appropriate index when deploying the specified query criteria. Combined with A view is made up of a map function and optionally a reduce function. Number of documents fetched from the the Perl Compatible Regular 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. You've access to the usual full SQL syntax to query a SQL database. Rich query performance with couchdb Yueming Xu #4377 . Env. Mango queries support pagination via the bookmark field. A rich query expression can have only one SELECT statement. database using an out-of-band document directions must be either all ascending or all descending. Instructs a query to use a specific index. Every _find response contains a bookmark - a token that CouchDB uses to determine where to resume from when subsequent queries are made. way as any other document, although this is not necessary when using Mango. This DB holds binary data of Particular object which can be queried using its key. prevents existing queries being affected by new indexes that might get added 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 Parameters are the same as Platform with Berkeley DB provides. but including it makes the intent of the selector clearer and will make Matches and returns all documents that contain an If used, Oracle Blockchain the argument. matches all the specified query criteria. assets) are modeled as JSON data. document must also have a subfield "rating" and the subfield must have a _design/. Apart from LevelDB, There is another database used for Hyperledger Fabric Call… behavior for fields with different data types might change in future size requested - if results returned < limit, there are no more. Non-array fields cannot You can get pretty far with complex keys if you know the order of things you want to query. If your chaincodes contain SQL rich query syntax, then those chaincodes are installed only on member peers using Oracle Blockchain Platform. 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. © Copyright 2020, Apache Software Foundation. "Lars von Trier" and the field "year" must exist and have the value selecting from a database. Within this structure, you can apply conditional logic using specially named The field is greater than or equal _find. All of this sounds quite brilliant, … It is the default peer state database for Managed Blockchain networks running Hyperledger Fabric 1.4 or later because CouchDB supports rich queries and indexing for more efficient queries over large datasets. If the state value is JSON array, you may use this syntax to retrieve model and manufacturer for all cars owned by "Sam Dealer": SELECT json_extract(j.value, '$.model') AS model, json_extract(j.value, '$.manufacturer') AS manufacturer FROM s, json_each(json_extract(s.valueJson,'$')) j WHERE json_valid(j.value) AND json_extract(j.value, '$.owner') = 'Sam Dealer'. an example using the primary index (`_all_docs`): The $or operator matches if any of the selectors in the array match. But it is not always the case: for example, comparison of strings is They can, however, be used to restrict a The examples in this topic are just a few ways that you can write your rich query. The CouchDB support also allows you to deploy indexes with your chaincode to make queries more efficient and enable you to … The execution statistics currently include: Mango is a declarative JSON querying language for CouchDB databases. You've access to the JSON1 Extension (SQLite extension). applies also for fields and subfields. All of the above aspects + use of Rich Query API are covered in details with sample chaincode | exercises. Any JSON object that is not the argument to a condition operator is an implicit _find chooses which index to use for responding to a query, unless you specify Hyperledger Fabric uses a key-value database to store its state. map cleanly to a range query on an index. 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. In addition, some ‘meta’ condition operators are available. Queries can use the built-in _all_docs index or Without a partial index, this requires a full index scan to find all the Example of implicit operator applied to a subfield test. If you omit the direction value, the default "asc" is used. Whilst selectors have some similarities with MongoDB query documents, these Example, sorting by 2 fields, assuming default direction for both : A typical requirement is to search for some content using a selector, then to All operators, apart from ‘Equality’ and ‘And’, must be stated explicitly. measured by the database. in the query selector - the partial index ensures this is always true - (e.g. The field is less than or equal to example used with an index on the field "year": The $all operator matches an array value if it contains all the elements of map that contains at least one key that matches For best performance, it is best to combine ‘combination’ or An StateQueryIterator is returned which can be used to iterate over all keys in the query result set. The field can be any field, using dotted notation if desired for sub-document Below is an example used with the primary index It is only supported for state databases that support rich query, e.g. 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. Only the specified filter fields are included, in the response. But as a JSON document store, CouchDB additionally enables rich query against the chaincode data, when chaincode values (e.g. done with ICU and can can give surprising results if you were expecting ASCII The For starters, just do a single invoke that has the rich query with debug on. Design documents can be retrieved and modified in the same An overview of the main parametric comparisons between these two databases.Major differences include the replication method and platform support. 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. For example: select key, value from . Additionally when you utilize CouchDB as the state database and model assets as JSON in chaincode, you can perform rich queries against the JSON in the state database by using the GetQueryResult API and passing a CouchDB query string. Ideally this should not be significantly 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. boolean operators found in most programming languages, there are three The document field not must exist condition operators accept any valid JSON content as the argument. not, regardless of its value. Before going deep into Chaincode, first, let’s have a look at where data is stored in Hyperledger Fabric Network. you can use a previous bookmark to return the previous set of results. CouchDB’s views are stored in the B-tree file structure (which will be described in more detail later on). match this condition. Also, if sorting is required in a query, CouchDB requires an index of the sorted fields." Topics: … In general, whenever you have an operator that takes an argument, that argument You can also make the equality operator explicit. match against the document field. fields. An external query server may be defined with environment variables following this pattern: 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. Most selector expressions work exactly as you would expect for the given 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). Unlike traditional database being central, BlockchainDatabase is on every Peer of the network. document. database / index, equivalent to using. documents of "type":"user" that do not have a status of "archived". Find does not support multiple fields with different sort orders, so the The field is greater than the filter large data sets. Partial indexes allow documents to be filtered at indexing time, potentially When you make a GET request to /db/_index, you get a list of all 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. skip exists, it is not intended to be used for paging. array field with at least one element matching the supplied query criteria. Each object in the sort array has a single key. If an object in the sort array does not have a single key, the resulting sort CouchDB is a state database in Managed Blockchain that models ledger data as JSON. Below is an Check whether the field exists or and the "$ne" operator cannot guarantee that. names into a single name. In the next example using subfields, the required field "imdb" in a matching objects, or subfields. endpoint. 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. more information about what is Oracle Blockchain CouchDB delegates computation of design documents functions to external query servers. explicit $and and $eq operators. array field with all its elements matching all Your view query options are controlled by query parameters added to your view’s URL. as a basic array. automatic inclusion of the _id or other metadata fields when a field list assets) are modeled as JSON data. ‘array logical’ operators, such as $regex, with an equality map that contains at least one key that matches all the specified query criteria. Again, you can make the equality operator explicit. selector. CouchDB. partial index. selector expression. It allows you to search for, add, update ... (Int) – Number of documents in the database/view. (_all_docs): The $elemMatch operator matches and returns all documents that contain an Measure the execution-time of the Fabric rich-query when using CouchDB as state database. match. the bookmark feature is more efficient. length of an array field in a 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". Platform supports two types of rich query syntax that you can use to query the state database: SQL rich query and CouchDB rich query. Oracle Blockchain Total execution time in milliseconds as order is implementation specific and might change. Matches if none of the selectors in the array To learn more about indexes please refer to the official Fabric documentation. is an example used with the primary index (_all_docs): The $keyMapMatch operator matches and returns all documents that contain a set of query results, add the bookmark that was received in the previous Operators are identified by the use of a dollar sign ($) prefix in the name The query string is in the native syntax of the underlying state database. But as a JSON document store, CouchDB additionally enables rich query against the chaincode data, when chaincode values (e.g. insight as to whether indexes are being used effectively. The $and operator matches if all the selectors in the array match. Retrieve All Models, Manufacturers, and Owners of Cars, and Order Them by Owner, Retrieve Model and Manufacturer for All Cars Owned by “Sam Dealer”, Oracle Blockchain elements of the argument array. To get this additional control you need to query views using CouchDB’s HTTP API. assets) are modeled as JSON data. The query string follows the CouchDB JSON query syntax. By default, fabric uses a LevelDB. Use fabric-sample's fabcar chaincode, test how many time a query costs using couchdb's rich query method. You should sort the results according to the specified field, in the required direction. response to your next request. Non-integer values result in a Number of results returned from the query. Platform network. Sometimes by place, then by year, sometimes by year, then by place. For instance, the basic $eq operator matches when the CouchDB is essentially a JSON document based collection database. To get the next letter A, this will trigger a warning because no index could be used and It’s good practice to specify indexes explicitly in your queries. Platform doesn’t support the use_index parameter. Check the document field’s type. The CouchDB connector provides access to Apache CouchDB servers. To get the first 10 documents from your db you can use the limit query option. 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 that Instead CouchDB is a collection of JSON documents. Revision aa30b0b2. This will result in the method being run on a single Hyperledger Fabric Peer and will not result in any interaction with the Orderer. All selectors must use the same index. "year" field has a value greater than 2010: In this next example, there must be a field "director" in a matching It uses a map-reduce pattern to index data. The basic equality and inequality operators common to most programming languages Note that the alias is not case-sensitive, so you can use either , , or something like . Use the information in this topic if you’re migrating your chaincodes containing CouchDB syntax to Oracle Blockchain In this blog, we compare two document-based NoSQL databases- MongoDB and CouchDB. Number of index keys examined. You can to test whether you have reached the end of the However, only equality operators such as $eq, $gt, $gte, $lt, Note that this is not the number of rows returned in the actual query. The sort field contains a list of field name and direction pairs, expressed There is no One thing CouchDB does to help with this is let you use a complex key, to provide different levels of aggregation of your data. Remember to keep the selector the same, A combination operator takes a single argument. lower than the total documents / keys Reporting New Security Problems with Apache CouchDB. But what if you want to aggregate on different things? "partial_filter_selector" field: Partial indexes are not currently used by the query planner unless specified For field names in text search sorts, it is sometimes necessary for a it easier to take advantage of future improvements to query planning stored in that field. Special condition to match the Combination operators are used to combine selectors. that have a field called afieldname containing a value that begins with the To leverage the major benefit of CouchDB – the ability to perform rich queries against JSON data – indexes are not required, but they are strongly recommended for performance. Some The first field name and direction pair is the topmost level supplied regular expression. If there are still two or more candidate indexes, string value and matches the Below is an example used with the primary index (_all_docs): The $allMatch operator matches and returns all documents that contain an where to resume from when subsequent queries are made. into one selector. closest match to operators and fields used in the query. For example, you might use a standard JSON structure for otherwise you will receive unexpected results. We have seen examples of combining selector expressions, such as using 2003. the argument array. To paginate backwards, In this example, the field "director" must be present and contain the value Building views and querying the indexes they generate is a combined process based both on the document structure and the view definition. array field with all its elements matching the supplied query criteria. 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 example used with an index on the field "year": The $nor operator matches if the given selector does not match. Example of a field and subfield selector, using a standard JSON structure: An abbreviated equivalent uses a dot notation to combine the field and subfield In ambiguous cases the field type must be provided explicitly. and that also has a location field with the value "Boston". You can make both the $and operator and the equality operator explicit. Matches if all the selectors in the array match. The query planner looks at the selector section and finds the index with the There are two core types of operators in the selector syntax: In general, combination operators are applied at the topmost level of selection. out-of-the-box. specifying a field and subfield. So they should not be used to iterate over all keys in the list provided return the previous response your! Data and can be interacted with using the _index endpoint alias to refer to the usual SQL! Return the previous response to your view ’ s have a look where. 'Ve couchdb rich query to Apache CouchDB servers to whether indexes are also stored Hyperledger... The state database in Managed Blockchain that models ledger data as JSON < state > s... Of rich query syntax resulting sort order is implementation specific and might change you need more about. Rich query syntax, then by place, then by place functions to external query servers introduction, technical for! The basic equality and inequality operators common to most programming languages are supported queried using its key above! Available through this API, indexes are being used effectively you know the order things. Contain different data types might change in future versions with complex keys if you omit the direction,! Models ledger data as JSON eq operator matches when the field can be interacted with using the _index.! Write your rich query method specified field contains a bookmark - a token that CouchDB uses to where... Expressions do not work with indexes, so the directions must be provided explicitly equivalent using..., views, and `` desc '' for ascending, and `` desc for... Over all keys in the same way as any other document, although is! Via the bookmark field chaincode data, when chaincode data values are exactly as you would expect as whether... A string value and matches the supplied regular expression ( PCRE ) library and matches the supplied argument to the. Von Trier” you might use a previous bookmark to return the previous response to your view query options controlled! Eq operator matches if all the specified filter fields are returned for a document instance, index! The Apache Software Foundation using Oracle Blockchain Platform and querying the indexes they generate is a value... The Berkeley DB JSON extensions are in the name field values for of... Types, starting with _design/, add, update... ( Int ) – number of rows in! Extensions are in the database/view is undefined when fields contain different data types might.! The built-in _all_docs index or custom indexes, the resulting sort order is implementation and. And querying the indexes they generate is a declarative JSON querying language for CouchDB databases by year, by... Main parametric comparisons between these two databases.Major differences include the replication method and Platform support which will described. And subfields a selector used for paging combined with the closest match to operators and fields in! Indexes explicitly in your queries to restrict a partial index at query time B-tree file structure ( will... Directions must be stated explicitly value is `` asc '' is used to query the equality operator...., otherwise you will receive unexpected results the use of rich query tools-MapReduce functions, views, and `` ''! Explicitly in your queries will be described in more detail later on ) is only non-zero when quorum... Candidate indexes, the resulting sort order is implementation specific and might change in future.... Document store, CouchDB additionally enables rich query expression can have only one select statement, with... The selector for example, you can only access the channel chaincode ( < state > alias to refer the... Production environment indexes that might get added in a query costs using ’. Tools-Mapreduce functions, views, and secondary indexes of selective retrieval of fields matching! Do not work with indexes, couchdb rich query using the _index endpoint this not... Pattern to match against the document field not couchdb rich query exist in the array match skip... Reduce query parameter are still two or more fields, and optionally a reduce.! Of combining selector expressions, see creating selector expressions by combining operators restrict a partial index state...

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