[Breaking] chore(GraphQL): Remove dgraph.graphql.p_sha256hash predicate and merge it into dgraph.graphql.p_query

[pawanrawal]

Fixes GraphQL-1017

We have also defined a new tokenizer on String of type sha256 which concatenates the sha256 along with the query. The first 64 chars represent the sha256 sum which is used to store the token. The second part of the input data is the query for persisted queries.

This change would mean that existing persisted queries don't work as expected unless the data for them is migrated.

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This change is 

[jarifibrahim]

would this be a breaking change for existing users?

Reviewable status: 0 of 16 files reviewed, all discussions resolved (waiting on @manishrjain and @vvbalaji-dgraph)

[abhimanyusinghgaur]

Reviewed 14 of 16 files at r1.
Reviewable status: 13 of 16 files reviewed, 2 unresolved discussions (waiting on @abhimanyusinghgaur, @manishrjain, @pawanrawal, and @vvbalaji-dgraph)

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ee/acl/acl_test.go, line 2176 at r1 (raw file):

exact

sha

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worker/export.go, line 651 at r1 (raw file):

		case e.attr == "dgraph.graphql.p_sha256hash":
			// Ignore this predicate.

should we still keep this, but move it below together with the dgraph.cors and the other removed stuff?

[pawanrawal]

Reviewable status: 7 of 16 files reviewed, 2 unresolved discussions (waiting on @abhimanyusinghgaur, @manishrjain, and @vvbalaji-dgraph)

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ee/acl/acl_test.go, line 2176 at r1 (raw file):

Previously, abhimanyusinghgaur (Abhimanyu Singh Gaur) wrote…

exact

sha

Done.

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worker/export.go, line 651 at r1 (raw file):

Previously, abhimanyusinghgaur (Abhimanyu Singh Gaur) wrote…

		case e.attr == "dgraph.graphql.p_sha256hash":
			// Ignore this predicate.

should we still keep this, but move it below together with the dgraph.cors and the other removed stuff?

Done.

[abhimanyusinghgaur]

Reviewed 7 of 9 files at r2.
Reviewable status: 14 of 16 files reviewed, 2 unresolved discussions (waiting on @manishrjain, @pawanrawal, and @vvbalaji-dgraph)

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edgraph/graphql.go, line 138 at r2 (raw file):

fmt.Printf("%+v\n", shaQueryRes.Me[0])

stale

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tok/tok.go, line 393 at r2 (raw file):

Quoted 9 lines of code…

	if !ok || str == "" {
		return []string{}, nil
	}
	// The first 32 characters contain the sha256 for a query in hex format so
	// lets extract and index that part.
	if len(str) >= 64 {
		return []string{str[:64]}, nil
	}
	return []string{}, nil

can be simplified a bit:

	if !ok || len(str) < 64 {
		return []string{}, nil
	}
	// The first 32 characters contain the sha256 for a query in hex format so
	// lets extract and index that part.
	return []string{str[:64]}, nil